Difficult to explain but here goes.
Your top lever is attached to the spindle by a broached square hole in the top lever and a square axle at the end of the spindle.
The axle or top lever is worn - the sloppy fit allowing the top lever to wobble. The screw only clamps the top lever down and prevents it from coming off the square axle - the axle or broached hole must be worn and the pin head is bottoming out on the axle, not providing downward force on the toplever - first off i would remove a tiny amount with fine files from the top of the spindle.
If this doesn't solve it the axle is well worn a small amount of weld ( very small ) could build up the square of the spindle axle to remove some of the play between the broached square hole and the axle.
The hitch could be a number of things, ive found this when the lumps have been knocked about with to make the lever sit left of center - its exceptionally common and often you cant tell its been done to make the gun "feel" tighter, what usually happens is the peened metal just "bites" into the underbolt, smoothing off the underbolt and bites with some fine stones may help.
