Clutch Spider & Top Plate Not fitting ?

Have replaced the clutch spider on a standard S3 150 and re-built the clutch to find that the orriginal Surflex Top plate no longer fits into the spider. If I take all the corks and plates out I can see the tabs on the top plate only fit into every other slot in the spider with a 1-2 mm lack of gap/clearance for the other tabs.
Question is, is this common and do I just grind a small part away from the Spider legs to make it fit or have I got the wrong part and need to order something else ?
Thanks.
Question is, is this common and do I just grind a small part away from the Spider legs to make it fit or have I got the wrong part and need to order something else ?
Thanks.