I have been able to remove glass without breaking it on the manual operated B body door mirrors. I put the whole mirror in the oven at 200 degrees. After about 20 minutes I removed it(using gloves of course). I then used a tool I have that is designed for bleeding brakes without help. It is a plastic vacuum pump. The pump came with a hose and at least one suction cup that attatches to the end of the hose. Place the suction cup on the mirror and build vacuum. Then just pull gently and the glue will be soft enough to pull the glass away without breaking it. I was able to save some good date coded glass this way.