I recently acquired a 1050 and decided to work on the (not working) mower deck first. I cleaned it up, painted it and replaced the seized tension idler pulley. While I was reassembling the deck I noticed that the belt drive pulley on the gearbox was loose and sliding up and down on the output shaft. NOW! This is a relatively easy thing to fix, just tighten the screws! SURE!, unless you own an old tractor. The set screws on the pulley are seized and will not tighten or loosen. Of course the 3/16th hex screws are recessed so the only tool that can be used is a allen wrench. PB Blaster didn't help. Heat - maybe, but the pulley is massive cast iron and will probably dissipate the heat before it gets to the set screw. Maybe an allen wrench/1/2" drive socket and pound the screws with an impact wrench until it strips the allen tip or the set screw. Try to drill the very hard steel set screw and use an easy-out (which never works) or drill the set screw out completely and re-thread the hole.
Other than these ideas does anyone have a "magic wand" solution for this kind of problem?