Hello Nick - have you measured the periodic error of the mount - you can do this by running the Guiding Assistant for 5 or 6 turns of the worm (I have a G11, whose worm turns in 4 mins, so if you run the Guiding Assistant for 20-30 minutes you can usually get 5 or 6 worm periods included).
The Guding Assistant also gives you advice on recommended paramaters for min movements in RA and DEC, and what to set for the DEC backlash.?
I have found that if the mount is accurately polar aligned, then DEC movements are mainly due to the seeing. The default PHD2 parameter for DEC aggressiveness is 100%, and I found I had to reduce this down to 60 or 70% to stop DEC constantly responding to changes in seeing. I also found that if there was a large DEC correction, it tended to cause a reaction in RA. Playing with decreasing the aggressiveness settings and increaing the min move parameter (and also increasing the exposure time of the camera to 3 or 4 seconds to average out the seeing helped). I also found it was worth running a guiding session for 20 or 30 minutes, since for my mount it does tend to settle down.?
I also believe the Losmandy mounts are better with higher loads - if you have a fairly small telescope, you may want to deliberately load the scope so it is east heavy. I tend to get a smoother periodic error curve when I put a 12" Newtonian on my G11 mount (which probably comes in at 35 lbs with tube rings and camera etc.) compared to when a put on a 102 mm refractor (which is only about 15 lbs).?
I have also been learning how to use PHD2 for autoguiding, and can now get RA errors down to around 0.8" and DEC errors down to around 0.6" on a good night, but I think I am limited by my seeing conditions as I live on the outskirts of a city.
I also recently stripped down and regreased my mount - I also put a small amount of grease onto the metal rods in the Oldham couplers - if for any reason these "stick" you may get stick-slip effects which I'm pretty sure could cause spikes in? guiding. You also need to be careful to not put too much grease on - this could also cause problems (e.g. the excess grease could make its way to the clutches, which you don't want. It is also possible to change the bearings in the worm blocks fairly easily - they are R4 ZZ 1/4 inch bearings.
Hope this helps? ?
