Thanks again Mike,
Think we are getting somewhere - will know tonight for sure when I get to work on it in front of me.
However, I think I've found a mistake in the manual, and its right at the point of my problem, so maybe this is whats wrong.
TAKEN FROM THE CAT SX3 MANUAL:
Step 5 - showing the 4x6x2.5 spacer going on BEFORE the bearing...
but in the exploded view (also in the manual and online) it shows this spacer going on AFTER the bearing:
So which one is correct?