From the Ten-Tec Reflector January 20, 2005
I know this sounds stupid but this corrected the RIT encoder problem for my Orion and another ham friends Orion. Take hold of the encoder knob and pull hard on it like you are trying to pull the knob off, then let go. Once I did that my encoder started working again and has worked and is still working today. This also worked for N4ZZ's Orion. Strange but a simple fix for us, so I hope it works for you. It might save you a trip to Ten-Tec.
73
John WB4QDA
April 8, 2007
There must be a plate through involved with the RIT control. Mine started acting up shortly after I bought my Orion in 2003. I eventually removed the top and bottom covers and removed the 10 screws that held on the front panel. I used my pencil soldering iron and re-heated the pins for the RIT control. It worked fine until earlier this week when I pushed the knob to reset it back to ZERO. Then it started acting up again. Yesterday, I went through the same process again and now the control is working fine. Be careful when re-heating the pins. 3 of them are close together.
You can do the repair by just laying the front panel on the knobs and do not have to unplug anything. Good luck.
73,
John W3GQJ
July 14, 2008
I took my Orion apart again today. My first experience with the problem was in September, 2004. Many times I had soldered the encoder pins thinking it fixed the problem. A year later it would come back and be temperature sensitive. Solder pins again and problem would quit. About three months ago I had the problem again and soldered pins. A week later it was back. So in frustration, I decided to master this challenge.
I removed the logic and display board today. Before I removed it, I gently pulled on the logic board and could make the problem appear. I then pushed on the board and the problem disappeared.
After I removed the board and carefully looked at the pins, pins 3 and 4 of J8 did not have any scratch insertion marks on them. I looked closer under a magnifying glass on noticed that pins 3 and 4 were slightly out of alignment. They were bent about 1/32 toward the display screen. I took a picture with digital camera and the misalignment is visible. (I am sending a copy to Ten-Tec for their files.) Using my finger nail, I bent pins 3 and 4 away from the display until they lined up with the other pins. I then
remounted the logic board / display board and then tried flexing the logic board again. This time I had no problem. Evidently the female connector sockets only have contacts on one side because of small size.
If the RIT/XIT quits before I "check out," I will let the list know. But I plan to try to reach the nineties which means I will probably have a different rig by then! 
Thank you everyone who sent me their observation and John, K1ESE, who worked on his rig this weekend and confirmed that the problem was in the area of the "B" ribbon cable.
73,
John W3GQJ
July 30, 2008
At Paul Clinton's urging, I performed your repair today, John, and my RIT and XIT are now working for the first time in about 3/4 years. This could be an oxidation problem that simply unplugging and plugging the connectors wipes off, but, I suspect that you are right and that a couple of the pins were not mating correctly. Nice catch after all the discussion of this problem!
73,
Stan, W4AG