Brian,
I have experienced all the mentioned troubles plus a couple others (minus the USALS issue) in the past while setting up my own personal dishes. Some were self inflicted (related to the flimsy gage metal of the SG2100 motor bracket and me trying to use it for "jacking" purposes).
I originally started out with an SG2100 motor, but when I started attaching heavier dishes to it it became apparent that it wasn't the route for me to follow. I started buying the DG-380 motors and have been extremely pleased since. I don't know if you sell these in your shop or not. I bought mine through Sadoun's (that's no reflection on your business or products - just a matter of where I found myself when starting out). The brackets of the DG-380 are very stout!
As for the USALS alignment, the best practice I have found was to start out with the nearest possible true southern sat first (typical approach). Use the most accurate longitude and latitude entries possible and set the motor latitude angle by reading the elevation angle from the flat belly of the motor with a gravity dial or a digital inclinometer and subtraction the reading from 90°. I don't get too excited about the setting of the dish elevation angle as there are so many other variables (motor tube bend / trying to read the scale accurately etc). I just fly be the seat of my pants on that part and use my SuperBuddy Meter or my trusty Coolsat 5K to get me where I need to be.
The items I start paying particular attention to from this point on are the centering of the dish mounting bracket on the motor tube axis, the backlash of the motor tube/gear assembly and the possible "droop" or side to side play in the dish bracket (the part of the dish clamping mechanism that fastens it to the motor tube). For the last case, a dish with a jacking bolt for the elevation adjustment is helpful as it keeps the dish from falling when you loosen the clamps to make a small tweak. If you don't have to focus on holding the entire weight of the dish to move it a partial degree, you can more closely monitor the flexing of the mounting brackets and keep that to a minimum to keep the assembly square.
I also try to avoid making dish elevation adjustments when the motor is positioned to the side of dead center. I test a satellite off to the side of the arc and if I need to raise or lower the dish elevation, I guestimate how much and command the motor to go back to zero first. Then I make the elevation adjustment there. This reduces the side pull force due to the center of gravity being off-center and lessens the chance that the bracket will twist and introduce a new and unwanted error.
The next step that I follow is a "calibration" routine. I didn't come up with this myself, I read it somewhere and it came from the president of one of the H-H motor MFG companies.
Once you have set up the nearest true south sat, you command the motor to go to the furthest receivable sat to either side of the arc. Then you tweak on either the dish elevation angle or the motor azimuth angle (but only one - NOT both). Then you command the motor to the furthest possible receivable sat on the opposite side of the arc and tweak on the other adjustment. You go back and forth from one side of the arc to the other and continue adjusting dish elevation on one side and motor azimuth on the other. You then work your way further out to the ends of the available arc and LOS in this methodical process. It doesn't matter which adjustment you make on which side of the arc, as long as you adjust only one and always only that specific adjustment on that side of the arc (in other words, stick to the same pattern throughout the whole process).
Not sure if my way of doing this is better or great, but I offer it as information for Mark and anyone else that desires to check it out. I wish your friend Mark better luck in the next try anyway.
RADAR