ive had a slight knocking noise from the front off side with a very slight wheel vibration. recently had all wheels balanced and fitted new wishbones. after looking at the top strut mounts from inside the engine bay and pushing down on the car the rubber bush appears to be split/perished.on the top mount/spring plate. has anyone ever heard of this before or ever tackeld this job. thanks in advance james .

Fairly common problem. Never had to do it on mine, but it requires usual road spring compressors & special Volvo tools to dismantle the top bearing.

I had these changed on mine at an independent, roughly 70 quid for parts and labour. It made a major difference sharpening up the steering. Note the garage recommended doing both sides at the same time since they both are likely to be in a dodgy state. Hope this helps. JW