96 blazer trans leak

I need som help, my 96 blazer's transmisson was serviced last year and had a new filter and pan gasget done. But now there is a small leak that seems to be coming from the shaft that the shift cable connects to on the side of the transmission. Does anyone know if this gasget or o-ring can be replaced myself or will it require a trans shop or dealer to fix?

thxs for any help