Update: I managed to slide the freehub + cassette back onto the hub - took a bit of persuasion, but easy once I had the technique. But the freehub now has a significant drag - when I rotate the pedals forward, the back wheel spin stops within a couple of seconds. Any ideas on how to diagnose?
New bike that I've been riding for a couple of weeks without incident. I took the rear wheel off as part of a deep clean. As I removed the thru-axle and took off the wheel, the freehub body (DT Swiss 240) and cassette simply came off together.
The cassette lockring is still as tight as normal, and I can't see any missing springs or other parts. There is a loose part inside the lockring - I think this is the end cap. When I try to place the freehub body + cassette back on to the hub, it slides on about 0.5 cm and then won't move any further - nothing obvious blocking it. I've tried turning it anti-clockwise while sliding it on, but that doesn't help.
Is there a straightforward way to put the body + cassette back on the hub? Or do I need to wait until I can visit the LBS on Monday?