Indeed, several of us have had bad results from non genuine idlers over the last few years. Even Lemforder, the oe siupplier, where failing in 6 months.
So the only reliable part is a vx genuine idler. Unfortunately they are expensive, and trade club only helps by about a tenner on this item.
They can be a bugger to remove and it's very easy to bugger the rubber boot on the centre tie rod ball joint it connects to if it's being awkward. Do not damage the boot, they are not a common part, are an individual size, and not available from the usual boot suppliers, not available from vx individually and requiring purchase of £200 odd centre tie rod complete to replace it new. Used would be easy, assuming the idler comes off the new assembly again of course.
Having said all that, your old idler might be easy and pop off with the tap of a hammer.