How to find out if my controler is fryed

I had some thing similar on my XM-3100 except not only did I drop power but it made a goofy noise like Amtrak locomotive like two power pulses then coast for a spell then two power pulses forward then coast. I could only get up to 18 or 19 MPH on those police speed signs in out neighborhood.
You said"I have had my 36volt Wilderness Energy set up for over a year and every thing was great until the other day when it seemed to lose about half power, when I checked the conections they were all good. But if I wiggled the wires going to the motor it would work fine." Can you elaborate on your motor for I did the same wiggling motor wires to controller. Now mine don't go at all. It did go forwards if I pushed it some times but now nothing. I am beginning to think anything with yellow, green, and blue wires is almost interchangeable with other controllers?
I hope my scooter is still under warranty. I can chat with eXtreme or Alpha?
Rusty

When transistors come loose from their heatsink, they are likely to overheat and fail. Perhaps replacing your controller will be the best solution, and any new unit should be checked to prevent a repeat performance! (Screws should have lockwashers and/or "Locktite" thread locking liquid applied, to reduce chances of lossening, and all wiring to/from the motor and batteries should be large, heavy stranded copper, with soldered on high-current connectors, that are protected from vibration damage or shorting out. Do not use cheap, flimsy wires or connectors! (someone with electronic repair skills and equipment may be able to replace the bad parts and repair your controller, but it may not be easy or cost effective)--Good luck, Bob Curry