I was determined to take the tensioner apart on my 15-91 to give everything a thorough cleaning/shining. The set screw however was determined to stay put. In the end ... I won ... but not without some damage to the screw slot. I was mad. I said some bad words. I tried to source the screw on the net, but the only thing I could find was to purchase an entire face plate for $12.00 plus shipping. I said more bad words summing up the probability of paying $12.00 for a teeny tiny screw.
Hubby said ... no problem ... old trick.
He drilled a small hole in a lump of wood then drilled the screw into it, the wood is now a vise to hold the screw.
Using a slot cutting saw (these things actually exist?), he widened and deepened the slot a smidge, then rasped the top to debur it.
Kind of nice having an engineer around the house
In hindsight, I should have let the engineer remove the screw in the first place!! I have zero strength in my hands.
Now ... need to get hubby to remove the two screws holding the motor housing to the body. I tried, they're tight .. and no way do I want to mess up those babies.