Dear Zipcrack, You should have no fear about using your SP10 Mk2. But before you do use it, get a competent person to replace all the electrolytic capacitors in both the power supply and the on-board electronics. (If memory serves, there are 8 in the PS and about 20 on-board.) Buy new Panasonic FC (for low voltage) and TS-ED (for the very few high voltages needed in the PS) caps from Digikey at less than a buck apiece. You can get the parts list from the service manual available on Vinyl Engine. If you live on the East coast, email me and I can give you a reference to someone who will do it for you and calibrate the table as well as replacing any other marginal parts. But in general transistors don't break unless they are presented with too much voltage or AC vs DC. This can usually only happen if an electrolytic that is now more than 30 years old get leaky. Odds are that at least some of those caps in your unit are already bad. But this is nothing to be afraid of and you should be using your SP10.
The iron block approach to dampening vibration of the bearing assembly in the SP10 is purely the idea of Albert Porter. His plinths (or the plinths he sells) have that set-up. It works, but it is hardly essential to the enjoyment of an SP10. If you cannot afford his plinth at this time, buy a Technics plinth until you can; the obsidian plinth will not lose value, as it is also collectable. Or buy any of the other excellent after-market wooden plinths that can be seen on Audiogon.
The iron block approach to dampening vibration of the bearing assembly in the SP10 is purely the idea of Albert Porter. His plinths (or the plinths he sells) have that set-up. It works, but it is hardly essential to the enjoyment of an SP10. If you cannot afford his plinth at this time, buy a Technics plinth until you can; the obsidian plinth will not lose value, as it is also collectable. Or buy any of the other excellent after-market wooden plinths that can be seen on Audiogon.