HP 7470A plotter -- repairing/replacing paper feed rollers

Have you taken the plotter apart yet and seen what this is supposed to screw into? It's possibel there's a missing bush or nut inside the plotter. Try measuring the thread on the defective one. I am pretty sure it should be 6-32 UNC if it's the original part. If it is that thread, then the problem is elsewhere. OK. I tend to use 'rubber' generically to mean 'elastomer' for things like this. I know it's incorrect. Is trhe hub straight or tapered? I think what I'd try at this point would be to nake ne hubs from metal (brass, for example) with a suitable taper (an external taper of this size is easy to make on a lathe by settign the top slide at the appropriate angle, of course). Then try 1 or 2 layers of heatshrink sleeving on it. At least you won't damage any of th eoriginal HP parts doing this, so you can always go back and try something else. It's at times like this that I wish I had contacts in industry/universities... Indeed. -tony