Executrix Responsibility??

What is the name of your state? PA

My mother died 12/02. My sister and I were co-executrixes of her will. A property in her name and my sister's is going into foreclosure. I was recently served papers saying that I am a 1/4 owner of this property. This is when I discovered that the deed did not specify right of survivorship. It has always been thought to have been inherited solely by my sister. Nothing to the contrary was ever pointed out by the lawyer for the estate and on the Schedule F Joint Property filed the property is indicated went to my sister. The lawyer handling the foreclosure for the bank says they need a quick claim deed from me signing over my interest in the property to my sister to remove me from the complaint. If I do this, can the bank come after me as co-executrix of the estate in the event of a default judgement?

No they can not. Probate is not involved in any way here. Your signature is needed as an heir and part owner of the property and has nothing to do with your former status as co-executrix. There is already going to be a default judgment, but when the home goes up for foreclosure, the bank is going to most likely have their own agent purchase the home or sell it to any interested buyer who offers a higher bid, thereby negating the default judgment since their only interest is in getting the home sold to recover a profit.