Hiho,
I am far from an expert on SP10s' problems. I have never had a problem with any of mine whatsoever. Either several years ago when I tried my first, or since then. Albert is probably your best bet as he has direct experience.
As for the DP-75, the DP-75 came after the DP-80, which was launched in 1976, which would have put the DP75 lanch into the very late 70s, or early 1980s. I have not had a speed problem with the one I have used. In fact I find it very speed stable - I thought it had to do with the bi-directional servo technology they had (or that they borrowed from Victor). I find it needs to be on an isolation platform, which tames the 'jitter' I hear. The resident specialist on DP75s/DP80s is probably Rauliruegas. Lewm may also be able to help you - I am sure he learned a fair bit about his when it was redone.
I am far from an expert on SP10s' problems. I have never had a problem with any of mine whatsoever. Either several years ago when I tried my first, or since then. Albert is probably your best bet as he has direct experience.
As for the DP-75, the DP-75 came after the DP-80, which was launched in 1976, which would have put the DP75 lanch into the very late 70s, or early 1980s. I have not had a speed problem with the one I have used. In fact I find it very speed stable - I thought it had to do with the bi-directional servo technology they had (or that they borrowed from Victor). I find it needs to be on an isolation platform, which tames the 'jitter' I hear. The resident specialist on DP75s/DP80s is probably Rauliruegas. Lewm may also be able to help you - I am sure he learned a fair bit about his when it was redone.