A tech friend just finished fixing the ground and putting new tubes and caps on a 1976 vintage 300 PS. The owner wants to sell it for $300. It sounds pretty decent through the Carvin 212 cab my buddy uses for testing in his shop, but neither he nor I know anything more about these amps than the tube complement, the schematic diagram he got from Fender and the info on the Ampwares "Fender Field Guide" website. Has anyone here had any experience with them? Is it worth trying to negotiate a deal, or should the model name have been "POS" instead of "PS"?