"When I bought the bike, the screw was broken off inside and the rubber grommet was snapped. I ordered the new screw and grommet, but they don't seem to fit... I don't understand how it was originally set up; if you look closely, there are still remains of the old grommet in the screw hole. Could someone take a photo of their own bike so I can understand how it's supposed to be mounted? Thanks!"
Also have a look at the YouTube video of someone removing the tank - 3:20 for the fasteners at the front of the tank. Also have a look at this YouTube video from 4:40 Hope this helps. I see that you've asked the same question on the Multistrada.net forum which is probably a better place for anything relating to the older air cooled Multistrada.
this pic clears things up, thank you! didn't realize there was a picture in the manual... as one user told me: The screw doesn't actually attach to the frame; it stays detached. It’s absurd. Basically, the left-hand screw is useless—the tank is only held in place by the right-hand screw and the central one under the seat." i'll be putting a washer there and some rubber bushing so it actually makes contact with the frame. thanks
..it's not supposed to attach to the frame - it's a suspension bush to allow for movement. There's nothing wrong with the design, just a bit tricky to attach the two fixings. The expansion of the tank is a much bigger issue which you will know by now or certainly will do when/if you check your air filter.
i see, i thought there is something wrong with the design because on the right side, there is a washer and it's tightly held in place, where as on the left the screw has like 5mm of space, thus allowing some movement, i can see how this was intentional, so i should just screw it in as is in the picture, no mods required? i can see in the video posted about the guy taking his tank apart, he has made a "mod" and added some rubber and a metal washer. cheers. which is kinda what it was on my bike, perhaps it is this modification which caused the screw to snap as it didn't allow some play?
Yes, you are right - the front two are shoulder bolts/screws and as long as the rubbers are in place*, you just tighten them down and it's done - yes, big penny washer to spread the clamping load on the rubber. *reading your message properly - maybe there is a rubber sleeve missing? - if you look on the side with no gap, that has probably got every rubber fitted correctly.
"which is kinda what it was on my bike, perhaps it is this modification which caused the screw to snap as it didn't allow some play?" From memory, the size of the thread is quite small in relation to the larger, locating boss diameter, so i think it was possibly "operator error" upon tightening or maybe cross-threaded and then sheared off etc. I don't know for certain but i think the shouldered screw design remained the same throughout - maybe rubber "top-hats" changed though?