2005 foreman fm manual shift help

Thanks for the help guys. So as I take the tour thru this page I can see I'm not the first to have this issue. I've tightened the bolt on the foot shifter as tight as it goes.but I cant find the answers im looking for. I know it's into the slot it's supposed to feed into because it wouldn't back off of the shaft even with the bolt loosened. The bolt wouldn't pull out but would rather free spin. So in my irritation I tried giving it an attitude adjustment to pull the shifter off of the shaft. Well instead It backed the whole shaft out. I'm assuming the splinned shaft and shifter need replacing. and also any YouTube videos you may of came across. Also I order to get this shaft back in I'll have to pull the rear cover off and also swing arm?! im looking thru multiple parts pages and I cant find the splined shaft for the shifter. also what gaskets will I need to place once rear is pulled. is it just a gasket for the rear cover. 2005