Merc 60 Trim Pump Oil Leak

[Kevin Jeep]

Hi: My 1997 Merc 60 elpto Was in storage for the winter in Michigan. The following spring I grabbed the lower unit and lifted it and employed the tilt lock leaver and as I did oil bubbled as air was sucked in a hole in the base of the pump (manifold ?). if I remember right this hole had a stainless steel Ball was swedged (Pressed) into it , there is a spring( I believe looking w/out a mag. glass ) visible in the hole now and I hope I hav'nt lost anything other than the steel ball . Now I don't know if there was water in there that froze and popped the the ball out or what but when I tried to re-fill the trim unit the oil sprayed right back out when I lowered the unit manually.
. When thinking about this and looking at replacement prices( The Rube Goldberg took over )& I found that I could start an allen type set screw w/thread sealer into the opening to plug it but I was wondering if there was a better way to fix it before I try this with-out spending a ton of money ( rebuilt lift = 400 $) or buying a lot of expensive tools that i'll use 1 time . In the photo the hole is located directly below the "Gold" fill cap . Your input would be greatly appreciated if you know anything about this or even have an idea .