Before moving anything, IMO, spray the internals w WD40, chain lube etc, grab a heat gun and some gloves. Slowly but surely apply heat and little by little rock back and forth (ja ja), use your hands as sensors to check for any rubbing, scuffing. Wait a little, and let that oil drip away, discard as necessary. The main goal here is lube those bearings, create enough of a clearance for any gunk to come out.
I have salvaged a few nitro engines bought from Ebay and thrown away from friends.

If need be, heat up, spray some oil into the internals and let it simmer, wait a day if need be, all that gunk liquefies. Patience, a vice and safety goggles will come in handy...

Good luck