Sticky fuel cap, which part needs filing?

My fuel cap doesn't lift up without a helping tug, which Parr needs filing to stop it catching?

I've added a very thin M5 washer to the two rear bolts and it doesn't catch upon opening anymore but requires pushing down quite hard to lock

If you look closely at it, you will see rub marks where it is hitting .

+1 on Joe's link. Also keep it lubed and fix it before it won't open at all!

For those who ride a ST1100 (the above discussion being specific to the ST1300), there is an excellent tip about how to make the fuel cap much easier to remove and replace on the ST1100 at Mike Martin's site, here is the link: http://koczarski.com/mmartin/Gascap.htm

I've done that, it makes a world of difference. The grease needs to be re-applied about once every 2 years / 20,000 miles, assuming you don't fill the fuel tank so full that fuel rises up the filler neck and touches the cap when you are finished fuelling. If you persist in adding those last few ounces to the fuel tank when filling up, the grease washes off quite quickly.

Michael