[TowerTalk] Alliance HD73 Rotator calibrate and mast bolt size?

[Gene Bigham]

The recent round of 80 to 90 MPH straight line winds in our area has caused a misalignment of my rotator direction indicator and the actual antenna position.

First, the indicator is centered on North and can go on the meter to the (left) South of West and on the (right) South of East.

Right now playing with the calibrate knob and turning the antenna, the azimuth indicator needle will travel to and show South (of East) but the antenna and rotator stop at about the 130 to 140 degree position and remain there, tracking of the sweep of the indicator needle seems linear from North to the stop point.  But the antenna will not advance past 130 or so to due South 180 degrees.

On the other side of the indicator when I rotate back past North toward South (of West) the indicator arrives at South with a deceleration of the degrees traveled compared to the indicator as the antenna moves past north to north west then west, and finally ends up at south west say 210 to 220 and stops shy of South.

I initially tried to use the calibrate button to adjust this but the above results are the best I can get.
  
This is Alliance Model HD 73 and has been pretty bullet proof until now.

The rotator initially torques on top of my Aluma tower top section in heavy wind storms until my antenna guy put a couple of self tapping large screws through the top plate and against the lower bell housing of the rotator to limit the rotation of the rotator on its mounting pipe.  This rotator sits on top of the top plate using a lower pipe mount, the bottom of the bell housing just sets on the top plate while the pipe goes down into the tower and is secured to the tower legs using U bolts to all three tower legs.

There are two options I am thinking about to correct the alignment.

First, place the indicator and rotator as far to the South (of West) position and then loosening the mast clamp and manually align the antenna to true south since the correspondence of degrees measured to degrees turned is different on this side of the rotation.

Or Second, place the indicator and rotator as far to the South (of East) position and align the antenna to true south loosening the mast clamp.

Which way am I safe to presume will correct full range of rotation and more accurate correspondence to the measurement scale?  I can get someone to turn the antenna in the rotator to true South when the indicator is in either the South (of East) or (West) position.

Anyone familiar enough with this rotator to assist?

The antenna is A3S so precise pointing is not absolutely required, rather ballpark pointing.  At this point I cannot cover the last 30 to 60 degrees across the south stops.

And if you know the bolt size on the bolt heads securing the mast pipe I can send my painter friend up his ladder against the tower, as climbing this small tower is impossible, with the correct socket!  So he can loosen then move and tighten the antenna into place.

If I am incorrect in this entire diatribe please let me know your ideas.  I plan to attempt this move tomorrow evening.