Ian,
also worth checking the outer rails as they have an area machined out to accept the point blade,and this weakens them and makes them more likely to distort and jam the tie-bar....
I did see one N layout, which had been moved from a cold damp outbuilding into a very hot centrally heated room,the expansion and shrinkage of the boards managed to destroy 37 sets of Peco points........some of them were bowed up from the boards more than 1/2 an inch ...not good!
Regards Trevor........