I know someone who got an old unit upgraded and modified to some "C" specification, which apparently makes it sound more modern. I can check who did the work but doubt it will be much cheaper. I had a new one back in the day- it was a revelation, but that was in the mid-’70s. I suspect it sounds pretty old school tube by today’s standards, but it’s a classic. I eventually "upgraded" to an SP-10 mk ii which was glorious in its day, but man, talk about microphony problems. Bill Thalmann runs a very good shop in Virginia- I’d also trust him with the unit. Perhaps worth a call though chances are, he won’t be able to give you a precise estimate until he opens it up.
PS: i dug back and found the references to my friend's unit. He had Joe Curcio do the work. I gather than the unit can be repaired by Curcio without doing extensive mods but you'd probably have to call him to get a range of prices.
good luck-
PS: i dug back and found the references to my friend's unit. He had Joe Curcio do the work. I gather than the unit can be repaired by Curcio without doing extensive mods but you'd probably have to call him to get a range of prices.
good luck-