Yes, as Cusser and 87mazda have stated, don't put any
silicone sealer on the cam plug at the rear of the head.
Silicone gasket sealer applied to a rubber, or rubber coated metal part, like the cam plug is made, will cause the plug to slide out of it's location when the rear cam cap bolts are tightened. The silicone makes the rubber slippery. I use the silicone on paper gaskets or metal to metal applications where you want a total seal between the two pieces, but I never use it on rubber unless it is a small dab where a paper gasket meets a rubber gasket........like on an intake manifold for a Chevy V8 or the like.
When installing the Mazda cam plug, I make sure the opening for it is clean and oil free, I install the rear cam cap after applying Ultra Grey RTV silicone on the areas designated in this diagram......
I make sure I don't get any of the silicone in the opening where the cam plug will install.
I don't tighten the 12mm bolts down on that rear cam cap until I place the clean, dry cam plug into the hole it is supposed to go into, then I tighten those two rear 12mm cam cap bolts while making sure the cam plug stays put as I'm tightening the two bolts.
Should look like this when it is installed properly.......
Sorry about not getting to you sooner.........since becoming a moderator over at Mazdatrucking.com, I have been spending all of my time at that site.......I'll try to start checking things over here a bit more!