cambelt tensioner bearings

having changed the belts a few weeks ago, today was its first proper run out, after an hour or so i was noticing a strange grinding/squeek type noise.. which actually caused me to call recovery, didnt want to risk it further until i,d checked it out.

covers off and all looks ok, so started it again, no noise, nice and quiet (ish).. then as it gets warmer it came back..

anyone experience changing these, can new bearings be pressed into the casings or is it new case and carrier ??