I've had this problem for WEEKS now and I am really getting upset

The glow plug in the 3rd cylinder from the front in my 1970 220D keeps hissing and spitting out a constant small amount of white smoke. (which I later found out was actually atomized diesel fuel) It's coming from the area marked with a red line in the posted picture here. I know that some kind of seal is being broken on the plug.

I've replaced that cylinder's glow plug twice already and it's been doing the same thing every time after driving on the new plug for maybe 10+ miles, one of them even separated into two pieces!

The last time this happened, the engine started making a type of clicking noise when I'd give it gas, then it started hissing and surely enough, when i pulled into my garage and popped the hood; white smoke from the glow plug...

I have no idea what's wrong or where to start... Do i need to clean/replace the prechamber, replace the injector, or what?!

This is an extremely fun car to drive being a 4spd and all, so any help to get it back on the road would be greatly appreciated!

Thank you, all