I was trying to remember where the Stardust fitted in the Kimball range. Big full console from the very late 1970s, if I remember right. I had the spinet version of it (or the next one down the range) for a while. Experience tells me that they all suffered from the same sort of problems around that time. The bigger the organ, the more possible problems you had! I was lucky with mine and it wasn't too bad and easy for me to fix at home. Mind you I was glad to sell it. I can recall selling a few of them in the store and then sending the engineer round soon after!
Still, if it's free, you don't have much to lose and you might just find a good one. The bigger Kimballs could at least make some good sounds, unlike the smaller ones which were pretty dire.
I'd try it out, and if it's working I'd take a chance on it. If you're using it for accompanying a choir you won't need all its gimicks anyway, just the basic sounds, I'd guess.