Thanks for the responses!
I shouldn't have trusted the previous recap, one of the no-name chinese capacitors C27 was open and C25 was leaky. There's still a linearity problem but I know where to look.
It also looks like there's a bad filter; one of the 500uf has been replaced with two 470s in parallel...not sure what's going on there.
Anyway, I'm on my way. Thanks again!