Sorry for your trials and tribulations, Uwe. Ampeg moved production overseas in '07, if memory serves. If it is an SLM-era amp, maybe the Kornblums were just trying to get even with you Deutschers.
All my old 'pegs have been virtually indestructible. Had a cold solder joint repaired on my '71 V4B in the late 1970s. From then on, nothing but a cap job & tuneup. In between those, it fell off the top of my 4x10 while being moved and suffered no ill effects. I also have a '72 SVT and a '73-ish V4 which have served admirably as well.
There are plenty of things that will approximate the sound of an SVT - but Rob is right, there is nothing that really sounds like one.