Is the dish now stuck down at it's limit close to the horizon? If so, I doubt that it is the reed switch. The fact that you say that it makes a lot of noise, plus the age makes me think that the motor just isn't able to "lift" the dish, but it WAS able to run it down toward the horizon, until it came to it's limit. I assume this is a mount where the big gears are exposed, and if so, they tend to get rusty or dirty, and it takes more power to move the dish. Basically, if you could move it one direction, but not the other, then the reed switch was working.
Mine will do this occasionally, although mainly when it gets real cold. I get stuck down near my west horizon, and can move west, but not east. To see if this is the case, have someone run the VBOX while you're pushing on the dish in the direction it's supposed to move, and see if you can help it move. If it's able to move with help, then I'd recommend doing a thourough cleaning and lubrication of the gears.
My mount also seems to have a few rough spots on the gears, and sometimes it gets stuck other places, but usually if it gets stuck, I just run it back in the opposite direction a few clicks, then it will get past the rough spot.
Anyway, I doubt it's the reed switch. I would have thought that you'd have been getting all sorts of repeatability issues where you'd have to re-sync all the time if the reed was starting to go bad. I wouldn't think that a reed would fail so suddenly and only in one direction at first.
I agree re SkyVision being WAY overpriced on their switches, however I bought one from them a couple years ago just because I was too lazy to look for one. However the switch didn't solve my problems.