Had a look at the pics
Check these points for movement, just apply a moderate amount of pressure up down and sideways
1. Camera to ( is it an off axis guider or a flip thing) , and how is it attached, screw or compression rings.
2. Compression rings ... Or is it just 2 point screws behind focuser, screws are notorious for movement.
3. Did you relock the focuser after focusing, check focuser movement
4. Atachment points for the scope to mount, check everything as they can come loose over time, particularly in a permanent place
5. Ok your guide scope looks like it's cantilevered over the end first glance would suggest it's not rigid, plus the weights on it .
6. Focuser itself , if you get any visible movement it's going to be a little difficult,
With one of your images, there's a sudden jump in the stars, plus movement, if I had this on my setup, I'd wonder if a cloud had gone over and blocked it momentarily, but it does suggest a mechanical failure of a fairly sudden sort not backlash.
Get back as far as these things.... And be critical
