sudden backlash - mxj 4.5:1

a friend of mine is send me an mxj 4.5:1.  on three separate occasions, he was fighting a fish and the reel suddenly backlashed on him.  he didn't touch the lever, and he's no idiot around reels.  so for arguement's sake, let's leave operator error out of the equation.  i've been fiddling around with this reel for the last week and was finally able to re-create the problem.  then i found what i THINK to be the cause.  here's the reel.....
 

 
i backed off the preset knob and noticed that it was very loose.
 

 
i taped an bamboo skewer to the knob and wobbled it back and forth so that you can see the amount of play in the threads. 
 

 

 

 
it may not seem like much in the photo, but when you actually fiddle with it by hand, the amount of play seems like WAY too much. 
 

 

 
so i think what happened is that the preset knob actually "slipped" one set of threads under pressure.  it is definitely an intermittant problem.  i ordered a new spool shaft and a new preset knob.  we will see if this fixes the problem.  anyone ever have this problem before?  alan

anyone ever have this problem before?

Guess not from the zero replies so far. Way to go 'Reel Detective' (yes a bad pun but worth it )