Another option to seal the shaft is to cut one from a spark plug boot. If cut in the right places, you'll end up with a "stepped" bore that matches both ID's. Mild Bill
I got my wiper setup completed with everything functioning as expected, but electric motor and gear box seemed to run loud, so I have had my help out guy reverse power to the motor. Tricky for me but not for him, so it turns out. It has required a diode and a relay to get it running and he even has it parking again. I have not reinstalled and wired it in yet, but I will do soon and report back on how it turned out.
Sorry guys, I was hoping to post a little more info that I have gained about reversing the wiper motor, but for now at least I am off the air due to health issues which could side line for a good few months. Keep an eye out for me later, Russ.