Have a Kato F9A, which runs perfectly. Picked up a box of stuff this weekend, 25 cars and 4 engines. All from early 70's. The Model Power GP-40 lights up but wont budge. The Arnold Rapido FP9A , the Con-Cor SD50 and the Atlas F-M C, all stutter if nudged, but dont run. Hoping its just dirty wheels and dry gears.I am fairly new to this and need advice to open them and repair or tune.