24 year old power supply with old dead capacitors.
A stacked Toaster setup is sensitive to power issues.
Pretty sure Newtek will still repair your Toaster if they are able. They are still fond of what they call "Gen 1/2". Just go to their website, register you card, then request an RMA.
I'd still go for a new or refurbished PS first and see if that does it. And don't settle for another used worn out 20+ year old one. Good Luck.
Plaz
