Voltage regulator problem?

I have an oven control board that will not work when it is cold. If I heat it with a hairdrier it works fine until the oven cools down overnight. The problem is getting worse & I need to fix it. There are few components on the board that could be causing the problem & I suspect it is the voltage regulator which is a L387A. There are a few caps, diodes & tranys (BC327) but I think the problem would be the regulator, would you agree with me? If that is the case the next problem is it seems the L387A is obselete, is there a substitute?

Does this oven control board have anything at all to do with a Reprap machine?

oh dear no it doesn't, I was looking for a general electronics forum. sorry.