On 27 Nov 2004 10:51:04 -0500, Allan Adler
wrote:


The shaft for the pinion floats in the "box", and the flat piece
inside is the spring that keeps tension on it, keeping it fully
engaged. Where the spring contacts the shafts, use a heavy grease,
it's slow turning, but needs the lubrication. IF, when the pinion is
fully engaged in the rack, the shafts hit the bottom of the slots, the
rack is worn out.

If it's not repetitive, then the pinion is probably reasonably
concentric to the shaft, and the rack is the problem. In the older
scopes, wear on the rack would take a very long time, but the newer
ones sometimes have plastic rack, or soft brass, which will wear
quickly.

RT-44 is used because it does not outgass, it stays where you put it.
Oil fumes on the mirrors are a legitimate concern, not fatal, but
cause for cleaning and collumating more often than they should be.

If the rack is worn, there is nothing that will even things out but a
new rack. I would be more concerned if there was slop in the
drawtube/focuser body fit. This is also compensated for by the flat
spring in the "box". The spring should press the pinion into the
rack, and also to one side of the slots the shaft runs in.