Hi, I have the same issue
Periodically, every about 5 minutes the RA drift and you can try to change any parameter, but the problem persist!
I have an AM5n bought the beginning of this year
It worked perfectly since two months ago, now it also produce a noise, likes a "toc" when move to the object searched or when reach the Home position
And It Is not a problem of the autoguide because mount drift also when I use it for solar imaging with Heliostar
I center the Sun and some times it drift a few degrees
