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My PMX initially guided beautifully. I was using 1-2 seconds guide exposures.
After about 10 uses and a gap of use of about 2 months it suddenly produced a bad spike in PE after about 1-2 minutes into the imaging.It would not last long but it sent errors to 3 on the guiding. This would cause a double star in the image.
It was either one of 2 things in the end. It might've been a bit of crude from the original crap black drive belts that SB got that are defective and shed material. There are several posts on this site about getting the later grey belts otherwise these black ones can cause trouble.
SB sent me a new worm. When I replaced the worm all this stopped. I was wondering at the time that perhap the worm got damaged because of the several times the mount slipped on its incorrectly factory set gears and perhaps caused some damage. After replacing though the original worm looked faultless. But there was a little bit of black crud on the pulley that the belt rides on.
So a bit of crud that lifts the belt when it rotates to that point could explain it. Especially if it was working well at some point and now does not.
This reminds me I have to get SB to send out replacement belts to me.
I am assuming the usual has been done here like a good polar alignment, no cable drag, not unbalanced especially at the imaging angle. I don't like piggyback setups as they can be nicely balanced horizontally but badly unbalanced at a typical imaging angle. I guess that would have something to do with not being centred properly.
Once I replaced the worm block it guided beautifully but the old belts remain so the possibility exists it could happen again if that were indeed the cause.
Greg.
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