On my boat 1141 I've had a couple of problems with the mast collar:-
Collar wearing gelcoat in the step tube.
Collar coming loose on the mast.
In conversation with RS Aftersales, Junior:-
RS have changed the design of the collar to give greater area for the adhesive to contact the collar, I can't recall whether there has been a material & adhesive change as well. I have seen on another boat the collar come loose and rise up to sit at deck level while sailing; the step tube throat was completely stripped of gelcoat and the laminate cracked in one day's sailing in moderate wind. On that experience if it happens it is a very good idea to contact RS. For me they were very responsive in not just changing the failed 7 collar, but also in checking out & changing where necessary my other two rigs as well; 9 changed, 5 later build standard from new.
Collar & gelcoat wear seems to stem from a property of the collar to become plastic under pressure and start to stick to the gelcoat. The gelcoat and collar wear, and the excess friction can also cause the collar to mast adhesive to fail. As well as the collar change above newer builds have been fitted with the Deck Ring, item 12 in the parts list. Accommodating the Deck Ring requires the step tube mould be changed, so cannot be retro-fitted. Hence the retro-fit, Item 13 in parts list, coming soon. This has only been added to the parts list in the last month I believe. Which, when it can finally be ordered, will be great for the re-sale value of older boats; as the only other option available was to part-exchange for a new boat.
I have used 250uM PTFE Friction tape on my collars, which certainly alleviated the step tube wear, though it couldn't contain the 7 collar's bid for freedom, adhesive fail.