I have a new BME 105. Recently, the throttle arm movement has become stiff. Also, the throttle doesn't close all the way causing the idle to be very high. What can I do about this?

First, have you modified the carb any? Removed the spring etc.? If not, take it off and take the shaft out and see if the plate has rubbed anywhere in the venturi causing this. Maybe just a loose plate.

No, I haven't modified any part of the engine. I didn't even adjust the needles yet. I did change the diaphragm cover plate to the one that you attach a fuel line to. Where is this plate that you are talking about?

I was referring to the one on the throttle shaft inside of the carb. You might have hit and bent the shaft which can cause it to seem sticky.
Is there any binding in the linkage that could be causing this? If not tear the carb apart and see what the problem is.

Oh and by the way adjust those needles or find someone to help you do that. Factory settings are just a ball park adjustment, NOT perfect for all environments.

Check the butterfly, it may have come loose.
You sure don't want the screw to go thru engine.

I took the carb apart and when I took the butterfly off, it seemed to be very loose. After everything was off and disconnected the arm seemed to be working just fine. I guess it was the butterfly. Can I put lock-tite on the screw? I haven't adjusted the needles yet becasue it is still breaking in, just one gallon left. Thanks for all your help.

Yes and adjust the needles from the first run.