Manual Log Lighter Valve key receptacle broken
I have a fireplace which uses logs. The manual natural gas valve in the wall is opened with a key (square hole). Previous tenant (I think) used a pair of pliers to open/close it, and it broke the shaft partially, now only a little bit sticking out. Replacing the whole valve is a big hassle - break the dry wall, take the old valve out, replace it, and then fix the wall. The valve is larger than 1/2" and can't find a replacement, I was thinking of just replacing the shaft. That way I don't have to break the wall.
Any suggestions to build the shaft end with a super glue or putty? I tried to put a picture of the valve here in the message but was unsuccessful. Appreciate any help in fixing the problem. Also, how to attach a picture with this message. Thanks. Lenel_1