I need to remember that the solution is almost always the 10 cent fix, not the 10 dollar fix.

Further investigation showed that only one of the manual hubs was actually locking, even though the cap would turn to the locked position. A disassembly, cleaning and lubrication of the offending hub was the solution. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Thanks for the responses.

John