I put her back together tonight and powered her up without any issues, so I may just leave well enough alone. The only thing I noticed was a fairly prominent hum when the volumes were all the way off. Not sure what that's from, but I could probably live with it. The amp has really nice tone. She still has all the original transistors and caps, which all seem in fair shape. I still think it would be safe to replace the 9158s with a pair of MJ15015s, as they are not germanium. I plan to leave the 3155 alone. Still, I've not heard that transistor issues cause hum. I've heard that it's usually the capacitors getting old.