Volvo 960 transmission diagnostics

I bought this volvo a couple of years ago, and as along as I've owned it it's had periodic tranny error light woes. The light used to come on rarely but over time now it comes on within a week of being reset. I've cleaned the W-S-E switch connections and flushed and filled the tranny with new volvo fluid etc. shortly after initial purchase. When the light used to come on there seemed to be no noticeable change in shifting but now when the light comes on it seems late to shift/like it slips. The codes I pulled up this last time are 5-3-2, 6-2-2, 5-1-1, and 4-2-1. The 4-2-1 is a battery warning probably nothing to be concerned about, just that the codes took a while to read. But, the other codes were not recognized by my machine, anyone else have any ideas? The sensor and such are a little expensive so I'd really rather not just start shotgunning parts.