I'm missing the power drive cap on my 1V and I'm having a difficult time locating a replacement. However, I do see several AE-1 power drive caps for sale... do you know if they are interchangeable?
I just tried it. The power drive cap on the AE-1 is much smaller than the 1V's cap.
However, if you can find one that is only a LITTLE smaller, you can drop it in the hole and cover it with gaffer tape. I did this with my EOS 3 and it works fine to keep the dirt out.