SubZero Freezer not defrosting right

[subzerohero]

Hi Folks,
First, the specs.

Subzero Freezer (freezer only unit)
Model # 201FD
Serial # P363762

Link to available service manual.
http://www.subzerospecialists.com/pd...s/200300sm.pdf

Next, the problem.
The evaporator coil at the inside top of fridge is icing over to the point that it eventually stops the fan from turning. This occurs even though it's only set at number three coldness level. I know this is an old unit and suspecting a worn out part is an easy conclusion to jump to. But this was timed with me sort of messing with it which is what I suspect caused its new behavior. Let me explain.

The freezer was working fine until I moved it across the street to a new house, at which time I, for damage prevention during the brief trip by dolly, removed both lower front grills, ice maker tube, and the two screws/nuts that mount the defrost timer to the underside of the front frame so I could tape it to the upper side clear of the danger of being smooshed if the thing slipped off the dolly.

After an uneventful trip safely to it's new home I decided to give the underside components a good de-dusting/cleaning before putting the removed parts back in place. That done, when I went to return the defrost timer to its original location. Holding it while trying to line up the screws
I in accidently caused the controls knob at its center to turn I'm guessing about a quarter turn but I can't be sure since I have no reference point to go by. All I know is it clicks when you turn it and it only seems to turn in one direction, there is a small mark on the timer body which is positioned at nearly the center of the knobs halfs right now. I suspect moving it has caused the defrost cycle to be altered enough to slowly cause the ice, as it takes several weeks for it to build up. Ive defrosted it manually once and it did the same thing. A few weeks, iced all up.

Anyway, to make a long story short, I don't know how to set or test the timer to know if it is doing what it should be doing. Can anyone offer any more detailed instructions on either? The subzero service manual seems to assume that the reader will already possess that diagnostics steps/specs knowledge. And frankly I don't want to go spending money on nonreturnable electrical parts that I may not need to diagnose the problem if I can avoid it.

This is all assuming of course that is the problem. I'm just guessing really, based on the timing of it all and the symptom. But any obvious or not obvious suggestions on other causes would be helpful as well if nothing else.
If you need pictures or more info just let me know
Thanks Much!

PS: I know the unit is quite old, but the thing is LOVED and we don't care about it's electricity use and whatnot, only that it works right again. Additionally we are not even close to being able to afford a new subzero.

[himeros]

This freezer will have a defrost timer, not sure where it is located however. Usually under the front kick plate just below the door, or in the back. There will be a small knob, about 1/4 inch with a screw driver slot. When you find this timer, make sure the freezer is on and running. The best way to proceed now is to unplug the freezer, and turn that knob clock wise. It will make small clicks as it advances, then will make a louder click. The first louder click is when it goes into the defrost cycle, and second louder click is when it comes out of the defrost cycle, and back into the cooling mode. After you can turn this knob and stop it at the right place, plug the freezer back in. If the heater coils and defrost limit terminator switch are working, the coils will defrost, if they don't post back for more help. If it does defrost, replace the defrost timer.

H.