I am updating this thread just in case someone has the same problem and is looking for a solution. Rather than replacing the whole engine case, I brought the bike to the local welder- he welded the drain plug hole shut, but was not able to drill into it and remake the hole. In the future, I will have to change the oil from the oil filter side and use a pump to get the little bit of oil that doesn't drain out because of the weld. Total cost was about $100. Bike is running great, though. The spark plugs were cleaned, new oil and I ran Seafoam through the tank. She's sleeping in the garage for the winter now, though
