gaz wrote:Brucey wrote:I think that your 'cassette' is actually an unusual style of Sun Tour screw-on freewheel, ... I think your freewheel uses a two-dog remover, not a four-dog remover as per the picture above.
Suntour abandoned two dog freewheels in the 80's.
I still think it's a Suntour cassette.
That cassette has a small diameter 12T spline on the lockring, like this one
the 10T spline in the OP's picture is rather different, being a much larger diameter, and I've only ever seen it on sun tour screw-on freewheels, as per my earlier photo.
If you look closely at the OP's picture you can just see the two notches for the freewheel remover, behind the lockring, partially obscured by the end of the QR skewer, that should look a little bit like this
Take the QR skewer out and if there are similar notches present it is a screw-on freewheel for sure. LBS will have a tool that will fit the two dogs.
If it is a screw on freewheel you just need a new one.
cheers
.