Looking for advice people of stw.

I have a 2012 Cotic Soul, 1×9 with an MRP top guide. Every few rides it becomes loose and I can move it by hand even though I had tightened it up hard when I’d put it on last.
Ive got no spaces NDS and just the guide on the drive side, would more spacers help? Thread lock? Anything else?

Cheers guys.