It looks great Chris! Been nice seeing how your images have been improving over the last couple of months
I would suggest that there may be a bit of grit or something on some part of the RA worm drive gearing. If it happens only once every 7-8 minutes (I calculated a while ago that the PE of an EQ6 is ~7.5 minutes), this is how long it takes for the RA gear to do a full revolution. If there is something sufficiently large (still small btw) bit of grit in the gear guiding likely won't help. If it is relatively small then guiding may help minimise the problem.
Over the New Year I decided to strip my mount down and give it a clean as it was starting to get some random spikes more often than you. This suggested to me that it was in the worm mechanism and not the RA gear itself. Working well now