Sorry, but I seem to have ( essentially ) the same problem... no positive lock. holding the button down while rotating the shaft to find the "best hold" then applying extra pressure sometimes helps. I had no problem with an older model. 400 XPR also seems to overhheat badly. My ultimate solution: purchasing the model 4000.
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Sorry, but I seem to have ( essentially ) the same problem... no positive lock. holding the button down while rotating the shaft to find the "best hold" then applying extra pressure sometimes helps. I had no problem with an older model. 400 XPR also seems to overhheat badly.
My ultimate solution: purchasing the model 4000.