You're just a tad late to 'the party' on this issue...China grease. I believe a search of this Forum's archives would find MANY reports...and common solution...to this issue in its day.
I have two gantry cranes of similar/same era...can't confirm stock numbers off hand. One has the magnet, the other the clamshell. Both 'froze' about the same time.
It was, indeed, a revelation to discover the grease issue upon teardown. I have no idea what spec the goop was brewed to!?!
Fortunately it was quite easy to remove with mild solvents, and left no damage to the basic parts...gears, shafts, bearings,....and belts, in my case. Hardest part was doing the first gantry, getting into the gear case, manipulating the snap latches, etc.. The second one was much easier.
At the time, I was working at our LHS. We had at least a half dozen customers call or come in with the same complaint about accessories of that generation, all having the grease issue. I was easily able to repair them at home overnight. Each one was easier. Honestly, I don't remember having to replace any belts...but that could just be my 80-year old gray matter having the usual recall issues of age.
I used LaBelle 106...white grease with PTFE, plastic compatible...for my own two repairs. To this day (at least 15 years have past) I can go to the basement, turn on the layout power, pick up the gantry controllers, and get instant, smooth, complete action from both. 
Later on I used Red n' Tacky grease, recommended by many on this forum, on PW engine repairs as well as the last couple of customer gantries of the same China vintage. It does, indeed, work very well.
Welcome to the 'fraternity', in any case!
KD
