I have a Carvin Vintage 50 i'd been wanting to do the Hasserl mods to for a long time but had been puttin it off. Well the other day my new tubes showed up in the mail so i figured it was as good a time as any to give it a shot. I'm happy to report my amp still works and the mods are great.
My point in posting is to encourage others, don't be scared! There's so much info out on the web now that you can get all kinds of directions. I did get lucky with the Hasserl mods since the guy has PDF's with pictures but even if you don't get so lucky Google probably has the answer you need. I don't know hardly anything about how amps work, and i'm not real great at soldering but i learned a lot by jumping into it.
All that being said remember to be careful, capacitors hurt. I know this from prior experience.