What gets to me is when well meaning people start modifying customers
equipment without a thought to the damage they might be doing to the
value or safety.

If I took my treasured vintage 1960`s Marshall amp to a repair shop for
a simple input socket replacement, and the 'engineer' proudly told me
that he'd improved it by boring holes through the circuit board and
modifying the sockets with shoelaces, soldered in a few extra fuses, or
rewired the preamp valves in teflon coated silver plated superwire,
glued the valves in with bath sealer and added a few extra ventilation
holes in the case, I might start thinking about suing for compensation.

Even a non standard fuse holder or voltage selector can reduce the value
of some collectable amps by quite a lot, and tinkering with the lay of
internal wiring can destroy that vintage sound.

On commercial gear like that, there should be no reason why a proper
lasting repair can`t be carried out using professional methods and the
proper parts. Anyone not prepared to do the job properly shouldn`t be
doing the job at all. (IMO)

Ron

When you have been into very many pieces of gear, you begin to see what
sacrifices are made in production to shave costs. A good example would be
RFI suppression and even underrated components. I suppose the purists would
want to maintain and even document all of the OEM flaws. It has often been
stated at the Antiques Roadshow, never to have repairs done as it destroys
the historical ambiance of the piece.

This is doubly true with electronics, where even new original parts have
crumbled to dust in the original boxes. I can't imagine anyone doing most
all the mods you described, but finding original parts in good order could
drive up the delivery time and price immensely. In this country, the ac
cord would probably have to be changed for safety reasons. You would want
to specify to the repairman up front that he might not be paid for a very
long time while he conducts considerable research in order to find the
originals. But if money is no object, perhaps an open account or a blank
check up front would be in order. The absolutely professional repairman
these days would tell you it's burned out and the parts are no longer
available and steer you to the showroom for the latest cheesy junk.