It's a diesel so check the fluids and get a good battery in it and fire it up. Don't fix what probably aint broken. If the fuel is bad but liquid drain it off, add new, crack the bleeders and let it flow a minute and then fire it up. Drain fluids after it warms up and you know it all is working again.
For the PTO use WD and heat. You cannot expect to go outside, spray with WD, and have it fall offnthere. Spray today, spray tomorrow, etc till it gives or heating it will go a long way.
WD is a fairly safe fluid for starting also. Or light a propane torch and stick it up intake while cranking can do alot to an old girl. If that scares you then let propane into the intake unlit while cranking works I hear too.