Cannot remove motor mounts, Would like some advice Options

[MaskedMan]

I would like some advice on a situation I'm in. Today, I was trying to install front and rear motor mount inserts on my Celica, but I'm having an extremely difficult time removing the mounts. At first, the bolts were just on extremely tight, but I managed to remove all the 14mm bolts on the bottom. My problem is with the front mount's through bolt. I removed the nut at the end of it, but the bolt is stuck on the rubber part and I am unable to pull the bolt out. I have tried hammering the bolt out, but it will just not budge. When I try to turn the bolt, the mount just turns with it, and when the mount cannot turn anymore, the rubber part begins to twist and twist even tighter around the through bolt. I do not want to damage the mount too much, because I just have new inserts, not new motor mounts. I'm at the point of just buying new mounts completely so that I can just be very rough and hack the old ones out even.

If anybody has any ideas on how to remove the bolt without damaging the rubber part of the mount, please let me know. Thank you.

[MaskedMan]

Thanks itchy, I wasn't sure if penatrent sprays would work on rubber like that as I always thought rubber would seal out the liquid. The mounts were actually under no stress at all. The way the car was set up, I had the engine supported up because the cross member was unbolted. I had planned on replacing it with a spare one I had with no rust on it, but I couldn't remove it fully. I couldn't get it free from the rear mount. The front engine mount was bolted only to the transmission with nothing underneath it. It was just hanging there, but the bolt still wouldn't come out, it's as if it molded together with the rubber of the mount.