No signal on a single transponder

[FuzzDV]

I've had DirecTV for about 3 years without any problems. But now suddenly I'm getting really patchy reception on lots of channels. I think I've isolated the problem: when testing the satellite signal strength, here's what I find:
- Good signal strength (80-90) on transponders 1-31 for both my Satellite In 1 and Satellite In 2.
- But on transponder 32, I get strong signal on Satellite In 1 (80-85), but ZERO on Satellite In 2 -- once every 30 seconds or so, Satellite In 2 will show a blip of signal peaking at about 70 or so.
- All other transponders are fine, showing good strength on both lines.

Any ideas on what might be causing this and how to correct it?
Thanks.

[Earl Bonovich]

Swap cables between tuner 1 and tuner 2, to see if the prolem follows the cable.

If it does, then it is either a cable, multiswitch, o rdish.

if not, it is the unit.