I have a Stihl fs40, engine runs great but the shaft gets so hot in use that it will melt the plastic bump head. I have a Shindaiwa T25 that won't run. Would it be possible to use the shaft from the T25 on the Stihl? A quick glance makes it look like it is the same diameter but the flex shaft inside would have to be the same as well. Any guesses? Anybody ever try this? Any other cure for the heating problem? I have greased the bearing even if Stihl made that difficult. The trimmer is out of warranty so what the hell, may as well try.