Squeaky pulley can I use PTFE spray?

[HSV Keith]

The pulley that takes up the slack on the belt Seems to have a slight squeak and I wondered if I could use something like GT85 which I believe is a PTFE equivalent of WD40.
I don't want to introduce some thing thats going to become a griding paste if it picks up dust & dirt.
I'm due for a service soon is it worth just getting it replaced.

[KMud]

Easy to replace if you need to, about £40-50 IIRC (part only).

[snowwolf]

Best to replace, it's been known to seize solid