I've made some progress with sorting out the new computer, but it's not resolved yet since I'm awaiting delivery of a new SSD. It transpires that the Buffalo SSD I have is not compatible with the latest motherboards, including the H81 in my new pc, so as a temporary fix, I've cloned the system onto an ordinary HDD. I can't believe how slow it is, even with an i7 processor and 16Gb of ram.
I have also made some progress with the Ricoh AP3800C repair which has been waiting for months to be resolved. The hard drive controller had stopped working and the only way I could use the printer was by disconnecting the HDD completely, thus removing some functionality from the copier. I tracked down a replacement controller board some time ago, but I've just been in a position to try it out. It was necessary to transfer the NVRAM and programme chips from the old board onto the replacement, since plugging in the whole unit just produced an error code. For now, it seems that the problem is fixed, but it needs some time to check that it's going to be reliable. When I get time I'll try to add some detail about this job onto the 3800 page of the website.