Bottom line for me is - do they make you happy?
It sounds like they did, but now they don't. So why keep them? Machines like 301s...there are lots of spare parts available, I don't think you need to keep your own. Something a lot more rare, maybe that'd make sense, but 301s are everywhere and parts seem to be pretty easy to find.
I think you should let go of the machines that don't thrill you, and focus on the ones that do! Maybe you can trade some of your machines for some neat 15 clones. Someone else will be thrilled to get some of the machines that make you yawn now.
