Hi folks: I've acquired a KA-3500 for not much money, it's a nice looking little amplifier and the casing / faceplate is in pretty good shape. It came to me with a blown left channel, so I'm working through trying to restore it. I made an initial shotgun pass to recap, and that did not help. So I've gone back to examine it more closely by checking voltages and so forth, and I have a batch of transistors to sub in as well, aside from the output transistors. There is a good signal coming out of the preamp into the power board, and I've already found out-of-spec voltage at R7 / Q1. It's sort of hilarious what I did not spot on my first pass through, you can see here that the top of the transistor Q9 is sheared off, and there are apparent cracks in the left channel output transistors. (The right side outputs are not cracked.) IMG_8413 by mikepick posted May 1, 2018 at 9:44 AM I haven't pulled the outputs yet for testing, but given the cracks the outlook is not good (in my limited knowledge), and so I've been doing the research into replacing them. I've read a few threads here where people have used the old transistors to hold down the new ones. If necessary, I'm looking at using the FJP5200RTU / FLP1943RTU to replace the 2SB618 / 2SD588. My first question is about pinout: according to what I find the 2SB618 / 2SD588 have a collector on the batwings as well, and the FJP5200RTU / FLP1943RTU do not seem to, if I am reading it right. If so, do I need to rig a connection from the collector to the heatsink? My second question is about mounting: are the batwings absolutely necessary? The FJP5200RTU / FLP1943RTU look to have a heat sink tab with a hole already, would I theoretically be able to drill and tap new holes to use to mount the transistors? Finally, I'm looking for good info on replacing outputs as well: thermal paste or mats, connections, etc. If any threads come to mind, I'm looking to read up on it. Thanks for reading this long-winded post. Any comments are appreciated.