It's possible that this has always been a design flaw at the point where you get the bad fit/rub. Todays rubber quality isn't what it used to be so getting 5 years out of the seal at this interference point might be considered good. If it happens both sides and you decide to replace with VP items you can keep the old ones and use sections of the old ones to repair them when the time comes. If it is a particularly odd shaped section I would guess that VP is the only source but there may be a simpler section available that will do the job just as well. Comments from other PV-ers who might have had the same problem are needed.