Help with vinyl frustration?


I guess it is my turn for some frustration with set up. I've read posts about it, but haven't encountered it until now.
I bought a new ScoutMaster about 4-5 months ago. I installed a brand new Dynavector 20XL which is supposedly a good match. However I have never sensed the magic that I believe this TT is capable of providing. I have checked and rechecked all calibrations. I have been up and down the scale of VTF/VTA. The problem persists.
The problem is that on certain songs on certain albums the vocals and upper mids/mid bass have a slight distortion. This might happen on one song and the next song sounds fine. This began just about the time of break in for the cartridge, maybe 50-75 hrs. As I said, I have checked and rechecked. I can find nothing wrong. I get the feeling that it is a very minor thing. Then sometimes I wonder if it is the cart itself?
I only notice this on classic rock albums which is what I play the most. I haven't heard this on classical albums. Which causes me to ask, Am I seeing to deeply into a poorly recorded record? But if so, why only certain songs on the album? And always the same place; vocals? This doesn't seem like an acceptable answer. Certainly if it is I guess I shouldn't have sold my MMF-7. However the SM kills the 7 on classical.

Anyone with any suggestions?
128x128artemus_5
Distortion can also be aggravated by too little vertical tracking force (VTF). I found this to be the case with a couple of cartridges I owned. In both cases, I was using an inaccurate measuring device. Once I got a more accurate stylus force gauge I was able to clear this up significantly. Finally, skating can cause distortion, but you'll typically hear it in a single channel when that's the case. Since it seems like overloading correction has solved the issue, this post may be moot, but hopefully still useful.
Artemus, doesn't K and K have a 1:15 or 1:20 step-up? Might be your cheapest solution unless you can trade your 20XL in for a higher output cartridge. If it were me I'd try to keep the LO MC thing going since that's my preference.
Dan ed
Wouldn't a 1:15 or 20 give more output? I was thinking 1:5 would be less, but maybe I'm thinking backwards.
Nonetheless the problem seems to have gone now that i have it turned down.
NO, you're absolutely correct. I'm having more and more of these "senior moments" lately. So you may be able to just eliminate the step-up. Worth a shot.
Dan ed, even though the Wright Phono preamp has 65 db gain and is able to accomidate the cartridge, when i tried a previous LOMC cart, I got a tube rush problem. However i think I had the cartridge loaded wrong due to my misunderstanding of loading. this may have exacerbated the problem. Maybe i'll try it without the tranny and with the proper loading and see what it does. But the problem does seem to be fixed at the moment. Thanks