[Farmall] PTO question

[Craig]

I have a Roto-Cutter bushhog style mower. Today while mowing, the pto shaft
came off of the pto/overrun clutch. When I got off to investigate, I found
the spring-loaded pin that holds the shaft on the mower had come loose. When
I looked closer, I found that the pin would not stay in the closed position
and it eventually came all the way out. It looks like the small end of the
pin had some sort of retainer clip in it that has broken. How do I fix this?

Thanks in advance.

Craig