Isolastic rubber buffer questions

Long time lurker and my first post--so be kind if this is a dumb question. I am getting my Commando ready for the riding season, and I found my Iso's were way loose. Not wanting to struggle with the shims any longer I got a set of Mick Hemmings vernier adjusters. They are beautifully made, delivery to the US was very quick, and with the Dollar pretty strong against the Pound these days,they are more affordable. The rear adjuster went in with no real problem, but I found my engine dropped down about 3/8" when I pulled the front mounting bolt out enough to remove the old left side Iso collar to install the vernier. I used a jack to raise the engine back in position and installed the vernier then torqued up the mount and removed the jack. The engine sagged again so the vernier collar was not concentric with the end cap for the mount, so out came the front mount. I found the bonded tube in the outer rubbers sagging about 1/4" off center in the rubbers. 35 years of gravity will do that I guess. New rubbers have arrived and I am puzzled as to what the two inner rubbers are supposed to do. The new inner rubbers I received are significantly smaller ( 1 5/8' OD) than the mount tube (1 7/8" ID) and the tight fitting ( 1 7/8"+ OD) outer rubbers. The old ones were also smaller and I thought they were just worn away as there was considerable rubber dust in the mount tube when I took it apart. It seems the inners, since they don't fit tightly in the mount, would do nothing and the two tight outer ones with the bonded tube would do all the isolating work. Also what keeps the inner rubbers tube and outer rubbers tubes in alignment until you fit the bolt? The bike has always pulled to the left hands off and I am hoping this and the Dave Taylor head steady I am also installing will help that issue. Any insight is appreciated.

The smaller inner rubbers are to limit motion in the vertical plane. The larger rubbers are supposedly composed of somewhat softer compound and the smaller inner ones are a little harder. I have some doubt about this, but no matter, the larger rubbers will allow freer movement until the amplitude is large enough to contact the inner rubbers which will more rapidly decelerate the movement. Sort of like progressively wound springs.

I'm not sure what you are asking in your second question. I am not familiar with the Hemmings adjusters, so am I to assume these fit with existing Isolastic rubbers? The late ('75) style rubbers are bonded to a single tube which eliminates any alignment issues, but with the older style, when you install the outer rubbers, they are usually tight enough to the middle tube to hold it in place by friction. If you are asking what keps the inner rubbers on the tube, it was friction olnly on the pre-'72 and in '73-'74 they added snap rings to locate them before going to the bonded tube for '75.

I hope this answers your question.