External shift mechanism cover removal

I have an '84 Voyager that I am dying to ride. I bought it with a broken shifter shaft. I am trying to remove the cover to access the mechanism. I havent gotten a manual yet but thanks to this cool site I was able to download it but it just says to remove the cover(around pg 80-82). At that point it does appear that I will need a special tool but I will cross that bridge when I get to it. I drained the oil, removed the foot peg,released the clutch cable and removed all of the allens but the cover will not budge. I did tap on the cover with a rubber mallet but to no avail. I have alot of experience working on vtwins and cars but this is my first inline motor so I need to ask the experienced. Any help would be greatly appreciated.
Thanks,
Matt

Sorry nobody has offered advice, Matt. I have no experience of that model, so can't help you. May sound stupid, but could you have missed a screw somewhere on the cover?
I hope somebody else chimes in with some ideas for you.

That cover isn't one that comes off willingly. It can be a pain to take off and put on. Usually it's because the shift shaft is tight fit so the whole thing has to kind of be wiggled off.

Resist the urge to pry at anything lol. If you must, though, there's surfaces close to the starter that aren't oil-sealing. Just remember that shift shaft will only allow a very small degree of movement or "wiggle" before you have to reverse and pull on the opposing side.

Hope it goes well for you!

Haha Biltonjim we were within minutes of each other!

i would have said the gasket is holding it tight, keep at it with a rubber mallet.
there is also a metal splash guard inside, make a note of which way round it goes

I make this suggestion but take no responsibility.
Try a knife with a very fine blade, I use one that is for opening packaging you may know it as a utility knife with an extending blade, usually dirt cheap and razor sharp.
Get it vertical, use a small hammer on the back of the blade and try to split the gasket it will probably run off but if you keep it vertical it won't mark the alloy. All you need is to open the surfaces slightly and it will part. Give it a go even if you do mark the mating surfaces it wont be much and ant gasket sealant will take up the mark.