My 10sp chain was hanging slack so i serviced the freehub. No difference. Bought a new 10sp freehub from Wiggle and installed all the bits that i took off – like spacer ring behind cassette and put the driveside bearings in from the old one (the new one came with no driveside bearings) – then installed cassette.

When i turn the wheel it sticks twice at roughly opposite sides.

I haven’t compared the freehub bodies to each other, just took the old off and put the new one on.

Any thoughts?

PS Ultimately i think the problem is with a tired old spring in the Ultegra rear mech. Oh well.