Wolfen, there a minor differences between 1894 and 336, but the idea will be exactly the same in the two. If all you have is a 336 go-by, use that. THe lifter and other affecting parts are identical.
You must take the action down. This is NOT a complicated process, but requires a little go-by for the first time or two. PM me and I will send a link to you where there are step-by-step instructions with solid photos. Easy.
As far as Locktite on the loading gate screw, yes, and I've done exactly that. In fact, I locktite them all except for the lever screw. And the only reason I don;t is because I clean it every time I shoot (necessitates removing lever, bolt and ejector) and it wouldn;t make sense to locktite. If I fire twenty rounds, for example, I've got to thumbnail or otherwise (with lever half open) turn that lever screw a tad. It seems to me to be the nature of these rifles.
Slicking the action? Once you break a Marlin 1894 or 336 down, as I mentioned in first paragraph, you may want to "slick" it up yourself...or not. In my very humble opinion, it should be done (if done by us) in increments, maybe a little each time we break down the action.