Hi Keen.
I'm not an expert on this, but are you using a wedge? It looks like the AZ-GTE is an alt-az mount. Without an equatorial wedge, stars will start to trail around the periphery of the image quite quickly.
Make sure everything is fully tightened and that nothing is slipping. This has happened to me.
It doesn't look like you can move the centre of balance on this scope, so with a big camera hanging off the back, this might be putting a bit of strain on the motor.
Also, the mount is rated for 5kg (although I can't find out whether it is for optical or imaging). The StarTravel 102 OTA is 3kg, and the camera + accessories probably weigh another KG which will put you close to the rated capacity. This could potentially be putting strain on the motor which would cause the stars to trail.
Also, make sure your mount and tripod are properly levelled before you start your imaging session.
As I said, I'm not an expert on this, but these are a few suggestions. I hope it is one of them rather than a fault with the mount. 🙂