Can't help with the cover but 5 springs, hell, is there a problem with the stop on the shaft being broken then re-positioned & welded on [but in the wrong position for spring tension]. My old yz490K [same technicaly as yours in that area] i broke the stop on two or three different shafts, [think one was an already cracked second hand off ebay]. The stop looks like some cast crap so i removed the stop of an old AG175 shaft [or something similar] which looked stamped out of good steel not a sort of cast steel & fitted it on which goes on a twisted spline [if that's the word]. Times which spline for spring preload then Bronzed it in place & was good until bike sold a long time after. Talking covers, i remember my YZ465G wearing out in the cover where the shaft comes through but still worked ok, just nor ideal or good for the seal. Think the cover is magnesium?--was a long time ago. ps, when the stop breaks or cracks to let the lever slip, it slips forward so reduces spring tension [lever runs into the case] which sounds reverse to your problem but if 'that' has happened who knows what went on after that to put it right. Sorry about the essay & i might be way off track with this.
