Continuing talking to myself...
Tonight, I am having a second night out with the mount.
Same thing - guides smoothly at 0.6-0.8"RMS total and then every 1-3 min RA spikes.

Out of curiosity I installed a counterweight (2kg). Luckily, I had a proper shaft and a weight.
Guess what? No more RA spikes/runaways!

That's with my smallish but very back heavy AT72 (ASI2600 and a filed-flattener).

I wanted to lighten my travel bag with this mount but it's not going to happen....
Guiding is really great at 0.6-1.0" RMS now.

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