[Steve Tinker]

Yes and yes.

When my first idler went, I also tried the replacement bearing rout. Bought good quality SKF deep groove ball bearings and (with difficulty) pressed out the old units and installed the new ones. Looked OK on the bench, but 5,000km later (on the annual service) when I checked my belt and tensioners, one new bearing was very gritty & the other slightly rough - they wouldn't have lasted much longer. I replaced them both with genuine Porsche rollers.

So be careful, as you need a good press and be very accurate with your alignment when pressing in the new bearings!