The oven actually doesn't work well, as it evenly heats up everything to the same temperature. What you want is for the bearings to be cooler than the heated up crankcase, thus the crankcase expands more than the bearings do. I would suggest a good heat gun like for heat shrink tubing or Monokote or a propane torch. With the bearings cool then heat up the crankcase on the outside and if you can't get the bearing to pop out, use a 1/4 brass rod with a flattened out edge on it, and a hammer to gingerly tap the bearing out. The crankcase is heated up to around 250 degrees, too hot to hold in bare hands so use leather gloves. The idea is to quickly heat up the crankcase and knock the bearing out before it heats up too. Old oil and crud can make the bearing stick, so you might have to use a brass rod to knock them out with.