too late:
Maybe it didn't ring a bell that you were arm-less.
There are several versions (or maybe two brands) which look similar, but one has side support arms and the other doesn't.
I just thought the newer ones were made lighter, and had the support struts.
Anyway, here is a little write up I did a while back for finding the LNB location on an unknown dish.
It requires a plumb pole, accurate elevation markings, and some clever azimuth alignment, but should work:
http://www.satelliteguys.us/1406345-post5.html
The Prodelin 1.8m has seriously accurate elevation and azimuth, so it should be a breeze!
Wish I'd thought to suggest this from the beginning.
Glad to hear you've got 'er peaked! - :up
Was talking to Linuxman today, and that is a nice performing dish, even on C-band.
Now, we need to work out a clever motorization technique for it! -