I recently acquired a used Paramount MX and I noticed that I was getting a spike in RA while guiding, The spike is on the order of 3 arc seconds, lasts just a few seconds and occurs every 5 minutes. Guiding RMS otherwise is extremely well behaved, less than 0.2" RMS. I attempted to correct it using PEC before realizing that it is not periodic with the worm. I have attached the graph of the PEC log so you can see that it seems to be exactly 1.25x the worm period. Any suggestions on how to proceed with troubleshooting?
