Years of crud. A good steam cleaning and flushing fixes them up.
I didn’t even worry if it was dry or not. Blow off the big drops, then run em wet to speed up the drying process, LOL. Those P2Ks are nothing but plastic and metal.
You can check for the axle twist without removing the gear covers (which can be a pita until you do a few and uncover the secret technique).
Simply invert the locomotive and try to turn each drivewheel by hand. If any of them move without also moving the opposite wheel then the axle gear is cracked at the bush. The axles are not solid through the gear. They are half shafts.
My first take is “bad wheelset/gear”. That’s a quick check of course. Just pop the bottom covers and pull a wheel set and see if either wheel EASILY turns by itself. If so, its likely the source of the noise. I’ve had P2K GPs with all the wheelsets in need of replacement, some with only one or two, and a couple with all OK.
You can check for the axle twist without removing the gear covers (which can be a pita until you do a few and