As too many have learned: It's those 2 bolt-bosses on the bottom of the cover that have a knack for cracking. Just looking at them tells you why. Very little "meat", there! One of mine cracked many years ago and developed a weep. Epoxy did the trick and lasted until last year when that weep turned into a leak. More epoxy was not an option so I took the cover to a machine shop that specializes in Aluminum and S/S. Before I took it there I washed it thoroughly with Lacquer thinner and "sneaked it
into the dishwasher to help ensure the best oil-free repair !
I now tighten the cover leaving those 2 bottom bolts loose, 'til last ! Once the others are tightened I merely "snug" the trouble-makers and with a new gasket - all is well. The only sealer I use is on the stator wire wire-grommet.
Something I did: After the cover repair I did the the smoothing-out of the built-up areas and taped a full sheet of "360" to a piece of glass and leveled the contact surface, I've done the same for the float-bowls and my cam-cover (3 sheets for that). Even with the smaller float-bowls it's surprising to see the Highs/Lows. Doesn't take much work and ensures a perfect seal with a dry gasket.