Probably an el46. You ever take a peek at the plug when it won't start? Is it really light colored? Also ever pull the muffler and look in there? I've seen some from that era with mild seize issues. If that's the case then it might be just a little off on compression. Couple of things I would try, ditch the decomp and "plug" the hole. (decomp plugs are cheap), also chop the cover like the new ones that let a little more heat out of the system. And last but not least open up the exit of the muffler, its a little goofy in that muffler exit area, nothing a die grinder can't fix. Most of the above is about losing a little heat from the system. I have found when those saw are like that, (slightly scuffed) I freshen them up by breaking the glaze and putting in a new ring. Then bump the compression and they start so much easier. Then those "cooling" focused mods seem to keep those from that era happier. Of course I've only done four of the el46 versions, all with issues; to this point so that's not a huge segment of the 562 population. I watched a couple of folks go around in circles tweaking the carb....I went for heat reduction and a compression increase instead. (after checking to make certain the carb diaphragms & fuel lines were good)