We have had some trouble lately with roller height issues. On the SP-15, the user turns a knob to raise or lower the rollers. Sometimes it works, sometimes not. The bearing blocks have an allen bolt to hold the roller height, but these will not turn either way. I’m hoping that if we take the bearing blocks apart and clean them thoroughly, that will help the mechanism perform as it should.
It is possible that when you tighten the screw, the outer edges of block meet before its tight on the post – I’ve read on line about tapping block with a blunt chisel near the inner edge of the gap to make it more parallel so that when you tighten the screw, it will be tight on the post – you might ask a mechanic or machinist about the exact technique.
I call Fritz late in the afternoon and almost always reach him. I have found that ordering off of his website is a good way to get an order processed in due course. NAGraphics is a small operation and the phone/emails can be overwhelming. Fritz is most generous with his time, but still needs to make a living.
Once we cleaned these up, they seemed to be in pretty good shape, with the exception of one socket head cap screw, which has slightly damaged threads. Nice to know they are easy to find! We also did the cleanout of the gap, and that helped too. They still seem somewhat slippery. I would love to know the advantages of buying new ones, and how to get NA Graphics to answer the phone! ;-)
I recently bought some replacements of these entire assemblies from NA Graphics and they were worth every penny!
If you are able to clean the blocks, rather than replace them, you should pull some very fine emory cloth (sandpaper) through the gap in the block – you are trying to make it open up a bit and cut down the sides a bit so that when you tighten the bolt, it will grip the pin that fits inside the block.
The “bolt” is called a socket head cap screw. The spec is 8-32 × 3/4″ and is available at any hardware store. It takes a 9/64″ Allen wrench.
The blocks are available from NA Graphics. Please note that only half of the “bolt” hole is threaded. Pass the screw through the unthreaded side first.
Update: We have cleaned the blocks pretty thoroughly. One has a bolt that is defective and hard to screw in and out. Anyone know where I might be able to get a replacement?