743 Hand controls disconnecting from pump

[oracle_of_ferndale]

The right-side hand control keeps disconnecting from the pump on my 743. In the picture with this post, (page 105 of the manual) the hub (#27) works loose and the lever (#19) cannot turn the knob on the pump. It has happened four times lately. I loosen the lower bolt (#23) in the lever to get the hub back in place, and then tighten the bold, hoping it will stay in place. Hope is not a strategy, and it is truly a pain to fix. Does anyone have a suggestion? Should I put loctite on the bolt? Is the lever defective? Only one of the hubs comes off, suggesting there is something wrong, but I can't see a difference between the front hub/lever and the back hub/lever. Thanks in advance for your suggestions.

 

[oracle_of_ferndale]

I was tightening bolt #23. Should have been tightening #22. Problem solved, I hope.