On ebay, I recently purchased a used Mitutoyo 800 mm linear scale for my UDR220 counter. It arrived here and looks brand new. The sliding portion (reading head?) seems to rock about with some slop but it slides back and forth nicely and reads perfectly. Does this sound normal for a scale? I haven't had one in my hands before. Also, a machinist friend told me they can be difficult to install. It looks rather straight forward to me, but I was wondering if there were any pitfalls that don't appear obvious to me. I haven't found any generic installation instructions anywhere. And finally, I'm looking for a couple of shorter scales for this counter, somewhere in the 300 mm range -- any ideas on where I could go looking to find a good used one, other than Mitutoyo?
Thanks for any input.