The ram rod is 0.375" dia. and so is the RR tubes bore.
As annoying as this is it puts the maker into a similar predicament as the early makers.
I created a scraper for the purpose of reducing the dia. of the shaft by drilling into a piece of 0.060" mild steel and counter sinking it, the countersink creates a sharp edge.
0.125" hot rolled steel would be more robust.
I am going to make a steel tube version for use and keep this one for show.