As you make preparation to leave The kenku Chukka and Clonk pass on some information.  "You will likely run afoul of petty warlords scavenging for soul coins and scrap metal to fuel and repair their infernal war machines. That's what we do for Mad Maggie.   We build, fix, and drive infernal machines."

You have see the two angrily hammering on a nonfunctional Demon Grinder.

"This one isn’t working, and we can’t figure out why. We would be very grateful if you could help us them discern the problem.  We might be able to help you out if you can help us out."

Seeing maybe some confused look at the mention of the soul coins they explain them to you, holding out one for you too examine.

"Soul coins are a currency of the Nine Hells and are highly valued by devils. The coins are used among the infernal hierarchy to barter for favors, bribe the unwilling, and reward the faithful for services rendered. Soul coins are created by Mammon and his greater devils on Minauros, the third layer of the Nine Hells, in a vast chamber where the captured souls of evil mortals are bound into the coins. These coins are then distributed throughout the Nine Hells to be used for goods and services, infernal deals, dark bargains, and bribes."

If you handle the coin to inspect it you can feel the soul bound within it — overcome with rage or fraught with despair.

"I don't know how much help I will be with this...machine...but I am willing to look it over in return for your assistance with our quest." Although not proficient in the knowledge of this type of contraption, Kaelani will inspect the vehicle, trying to understand the workings and connected pieces...

Arcana/Investigation: 14

...and cannot make heads nor tails of the thing!

Any one else can make a DC 15 Intelligence (Arcana or Investigation) check

Tibi flips his own coin in the air saying “I’m perfectly happy with mine thanks”. Drabash growls “pass it here!” Investigation check = 11

Darvin Arcana: 14

Oddly enough it is Drabash who notices that some sort of spiky gear seems to be disrupting the flow of infernal energy through the vehicle. The kenku nods at the revelation "Ah, yes the gear, comprised of spikes from a hezrou demon, interestingly enough. It seems to surge with demonic energy to cause the malfunction.  Very good.  But we can't fix that.  Do you know any spells like dispel magic?  That would do it."

The kenku look to you hopeful that you some sort of spell that might disrupt the evil energy.

Kaelani thinks on the problem and how to dispel demonic energy... (Arcana/Religion: 5) "I can counter spells, and I can contain fiends for up to an hour, but I am not sure either will be helpful..."

Drabash turns to Tibi with a grin saying "looks I've got hidden talents Boss."

Quote from Paladin54 >>

Do you know any spells like dispel magic?  That would do it."

"It just so happens that I do," Darvin replies with mix of self-satisfaction and relief as, for this moment at least, there was a concrete problem in front of him that could be solved in a simple and straightforward way using his skillset, giving a momentary reprieve from the grand scope of the seemingly intractable quest he'd found himself dragged into.

"Let's have a look," he says, stepping closer to the vehicle to get a closer look at the gear, and leaning in to squint at it as though trying to piece together how it all worked (possibly even giving a convincing performance to make it look like he knew the first thing about fiendish self-propelled transportation devices). "Ah, I see the issue," he lies, before extending a palm toward the offending gear while muttering a brief incantation.

Dispel Magic CHA check (if needed): 19

Chukka and Clonk clap their hands and thank you profusely for the help with the machine.  It seems your spell has worked and they are able to get to work getting the rest of the infernal machine running.

"Maybe you want to test the machine out and give us a ride to where we're headed? You can collect scrap metal on the way..." Kaelani asks/offers.

Tibi looks at Kaelani and sighs "listen Sobpia you can ride in this thing if you want but I ain't going anywhere near it - thanks very much!" At this statement Drabash nods fiercely in  agreement and says "you're so right boss we walk don't we!" At this Tibi sighs and says "you can walk Drabash my lad but me I'll fly thanks very much!"

Chukka and Clonk look at one another and then nod their heads in agreement.  "Ya, ya, we can give you a ride.  This one seats eight so plenty of room, much faster than flying.  Safer too,  Lots of trouble out there, other warlords fighting each other, demons and devils.  Not so safe."  Clonk says

Chukka slaps the armor of the Demon Grinder "Very tough, tougher than your armor I bet.  Very safe, very fast."

Demon Grinder

Tibi looks at the construction dubiously "exactly how much faster than flying and safer how?" he asks before finishing "if, and only if we decide to ride in this contraption exactly what is it going to cost us?" 

Drabash tries to nod sagely "good points Boss!"

Clonk nods his head up and down, "Two, three times faster than you can fly!  Very fast.  No cost either.  You help us fight if other warlords or anything else attacks and we give you ride.  We can scrap along the way.  Then we both help each other."

Chukka also adds, "As thanks for helping us fix machine."

Still dubious Tibi agrees to ride in the contraption.

"Let's go then!" Chukka says.  "Let me show you what this baby can do!"

He starts to show you the machine, pointing out the weapons and armor.

Demon Grinder

Clonk advised that each of you can handle one of the weapons.

One of you can take the Chomper

and the other two can handle a Harpoon Flinger each

Clonk beams proudly at the specs and abilities of the Demon Grinder

"This baby is a bulky, armored coach that rumbles loudly as it crushes obstacles and enemies in its path with the help of a swinging wrecking ball and iron jaws that are mounted on the front of the vehicle.  She handles like a garbage truck someone once told me.  Not sure what a garbage truck is, that guy was kinda odd, from some strange plane.  Bulky and big is what she is."

As you each choose which weapon you will run the two Kenku get the grinder started up.  As you set out Chukka yells to Tibi "I get your reluctance, but once you can see what this thing can do, and how bad it is out there, you'll be wishing for your own Infernal War Machine.  This thing is a trip!"

Kaelani grins, and looks at Tibi. "Well, boss, what are our assignments?"

Tibi looks over at Kaelani and grins maliciously "you my friend get to ride up front with the Chomper, Drabash gets the Wrecking Ball, while  Darvin and I will look after the Harpoon Flingers." 

Kaelani's grin becomes a child-like smile...it seems the chomp-seat is exactly where he wanted to be!!