I have a 1984 or so vintage Airens riding mower . 5HP briggs vertical shaft engine . It started blowing oil out the vent tube . Backfiring while cranking . I replaced the head gasket . It looked like it may have been bad . Would this cause the leak ? Now it will not start . Looks like it has no spark . Bad coil ? Seemed almost like the timing was over advanced . Could this slip in any way . I don't remember hitting anything . i removed the flywheel . The condenser wire looked crushed but still intact . I taped it to stop shorting . Is the condenser part of the coil or sold separately . Any to test the coil ?