funnily enough exactly the same problem as my track has some seized links its taking a lot of pulling up and like yours its slipping on the shaft.  I think the shaft is plated so not sure it will rust, but I am sure getting rid of the grease will help.  Frustrating, really they need to have a tooth mechanism rather than a clamp on a shaft.
		 
		
		
		
		
		
		
		
		
	
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