Volvo Penta steering actuator leaking near blue end cap - not shaft seal

[ccrobin]

So I just pulled my actuator to replace the seals as I have read how they often fail on these units. I noticed while part it looked fine. Seals looked intact. I replaced the shaft seal and wiper seal anyway, as well as the o-ring for the blue cap and put it back together. To test before re-installing I plugged the line connections and worked the ram. I was shocked to hear air sucking. It sounded like it was coming from the blue cap. After looking closer I see there is a factory hole that was machined into the end, which looks like it had been plugged with a threaded pin. Air was leaking quite easily past it (this is also where I saw the ATF leaking out and has assumed it was from a faulty O-ring there). My question is what is this for? Can I plug it with JB Weld (or some type of epoxy), Is it supposed to breathe like this? Seems this is the source of my problem but not sure the best remedy. I really don’t want to fight to re-install it if I will just need to remove it again. See attached photos. Any insight would be appreciated!

 

[monster1]

I just rebuilt my steering actuator and replaced the piston rod last year. I dont recall seeing anything like in your pictures. Is the hole threaded?