Ok, I've read and read and read some more. I see there's been a few (hundred or thousand?) who have had some problems with the Ampeg Portaflex 350 & 500 heads, (not sure on the 800's). I have an old Ampeg B-15T that I'm planning to upgrade with a new speaker in the cabinet, and a new amp on the flip-top board. I'd like,to go with an Ampeg Portaflex series amp for obvious reasons, but also for that Ampeg tone the PF series can produce (sounded great in the store). They also seem to be priced fairly for the features and power output. I'm looking at the PF-500, which will be driving the 8 ohm speaker in the fliptop most of the time and a 4 ohm load when I need the extra cab for big rooms or outdoor gigs. My question: is the problem "fixed", or are these amps still failing at an unacceptable rate?