If there are no clutch plates inserted the hub and basket will rotate independently of each other. You can easily make a clutch holding/locking tool out of one of your old friction plates and one old plain steel plate. Rivet them together, then place them in the clutch basket, which should lock the basket and hub together stopping them rotating separately.

Then (as Jim says) you can put it in gear and hold the rear brake to get everything locked up – bit tricky on your own though.

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