'91 Tercel - Wipers work on high only

Hello:

The wipers in my 91 Tercel ceased early in the summer (it didn't rain much...so I put off the repair for a couple of months). I removed the upper plastic cowling (below windshield) and removed the old pivots. The centre pivot (operates passenger side wiper) was rusted solid and wouldn't budge (even after a long soaking in Varsol), the driver's side pivot was fine. I was able to replace the entire mechanism with a replacement from the local wrecker.

Now I have an electrical problem.... I probably (occasionally) left the wipers on low while ceased. Now the wipers only work on high, and will not park (i.e. they stop immediately when turned off and don't return to bottom of windshield). The wiper fluid motor works fine, and the fuse that controls my wipers checks out ok.

Any idea if this problem is related the wiper switch located on my steering column, wiring between switch and motor, the wiper motor, something else...or a combination?

The wipers have a high and low setting (no intermittent setting), i.e settings are "Mist, Off, Lo, High".

Many thanks,
Norm