Well..... after hearing all of these responses, and knowing that I do not have the knowledge or skill to do this amplifier the justice and investment it deserves, I guess I will need to verify that the unit works, as least the power supply portion and make sure its salvageable and offer it up to someone who has the knowledge to bring this guy back to life. I purchased it hoping it would be an easy repair and you just needed to replace the tubes and viola! obviously I was mistaken!
James
It might help to post your location - there may be some local kindly AK'ers who are willing to work with you on doing some initial checks. As others have said, if you have an interest, it's a good amp to learn on and if you get it up and running, it's a nice sounding amp with a lot of options for modifications.
I upgraded my working ST-70 with a new driver board, so I have my original driver board available. If you want to give it a go, it's yours for the cost of shipping. One option would be to replace your unknown status board with mine, which will eliminate a lot of components as possible failure points and my 7199 sockets are fine, so you wouldn't have to clean/re-tension the ones on your board.
It will still require disconnecting (cutting or de-soldering) all the wires from your current board and being very careful to label them and note where they need to be re-soldered to my board. If you've never soldered before, you again may want to have someone who has there to help - or at least watch some videos and practice a bit before digging in. The can cap (silver cylindrical capacitor visible from the top of the unit) would still be a question, as well as there are a couple of caps underneath that would also possibly be bad. But you're down to a handful of components, and while aged, they may still be okay enough to determine functionality.
A local AK'er may also have some old tubes that could be used for a quick check versus your having to buy a whole set. Many of us have weaker old tubes that have been set aside as not good enough to use as daily drivers, but good enough to use for a functionality check.
If you can determine that all the transformers are good and it's working, you can then decide the path for restoration and possible mods/upgrades. While your chassis has rust issues and is dirty, if you can do some basic cleaning and stop any further rusting, it's just a cosmetic issue and you can determine whether that bothers you or not. if it's not going to be your long-term tube amp, you can use it as is and it's rough condition will just be a reminder that you brought a piece back from the scrap heap.
The point is, you may have some options if you don't want to give up on it just yet. Good luck and if you're interested in my driver board, just PM me.