Yes, it is very possible that you have fried either one, or both, transistors. Germanium Transistors are extremely heat sensitive. What I recommend is that you get a set of transistor sockets and try some cheap NPN transistors in place of the expensive OC140's. Look for some NTE101 or NTE103A's at your local electronics store and try those.
If that fixes it then decide if you like the tone of the NTE's and if you do great leave them in, if not, try using one old OC140 at a time and one new NTE to test to see if both OC140's are bad. If only one is bad replace just that one. SBE has tested OC140's for $9.50 each. At that price no use replacing them both if only one is bad. Be
careful when you remove the current transistors as they may not be bad and you may use them again.
Here's the links to the SBE components:
SBE Transistor Sockets and
SBE OC140's