Since you are removing the nuts I think I would replace the old sealing washers with brass washers.
This is interesting to me. Didn't think of that..Thinner washers run the risk of the threads topping out in the acorns nuts so you do not get a reliable torque setting. Naughty me used 3mm washers instead of 3.175mm, but they worked.
Brass from Amazon.
These are what I bought. Less than a dollar a piece. 2mm thick, have used them on 2 motors with no problems.Got a link? Thanks!