The plug is still there,the gear leaver moves freely I have tried rocking the bike applyng pressure to the gear lever but to no avail its jammed solid in 5th
if i have to take the box out,and seeing how complicated it all looks what do i need to look for?
Not sounding too good. What to look for 'in there'? Well I'm not a mechanic, but from what you say, it sounds like probably something to do with the selector mechanism; something stopping the drum rotating, stopping one of the forks moving, or the activator pawls attached to the gear lever not engaging.
Now that might sound complicated, but it isn't. I've just stripped my '95 1100 gearbox, and the selector forks, then the drum, are the first parts you remove once the box is open. So any problem with these should be apparent. If nothing is, then once these are removed you can see the selector pawls at the bottom of the box; again you should be able to see any obvious problems (damage) to these. Thinking about it, this could be the most likely candidate. there's a 'return' spring here, it moves them back in to position for the next shift, once you release the pressure on the lever; if that's broken, they won't move back. (Better check it on mine, used to get stuck in fifth occasionally).
If all is OK here, then you'll have to check to make sure the gears are sliding on the shafts.
If you do a strip down yourself, get a manual (I've got Haynes) and follow it, you shouldn't have any problems taking it apart. And providing no bearings are displaced, and you haven't mixed any shims up (no problem on mine, they're different diameters; don't know about an 1150 box), you shouldn't have any problems getting it back together.
If bearings are moved, then you'll need micrometer for checking shim thickness, and Dial Test Indicator set-up for checking end float. That's when it starts to get a bit more complicated.
Up to you; how confident you feel and what tools you have or can lay your hands on. A dealer will not be cheap, you might feel out of your depth. I think I might take the line suggested by digger, and try to get a replacement box. Again not cheap, but it would beat a dealer/mechanic. You could do the replacement yourself, and then you'd have the old box to investigate at your leisure. If you fix it you've now got a spare, if you don't, you haven't really lost much.
Just my thoughts, no doubt somebody will be along soon to shoot me down
Good luck what ever...
Edit Just had another read of your first post. What sort of 'noise' did/does it make when the clutch is engaged? The reason I ask that is that mine sounded like a bag of spanners, and I had a bearing gone. What colour was the oil you took out? Any shiny metal flake effect? Any bits of metal/metal powder stuck to the drain plug? I ask about the colour because apparently, when the sealed ball bearings in the later boxes get damaged, the oil changes colour. I won't say what to lest I give you 'oh shit I've got that' syndrome unnecessarily, it's mainly related to problems with later 1100 boxes, don't recall hearing of it applying to 1150, but youi never know.
Dave.