I have that problem also. Happened on 2 ECU boxes I have.
One sat on a shelf for years and all the sudden it started running out.
Other on one was on my 'cuda 40 years and about 3 years ago it started running out.
No idea why.
When I saw Mr Cuda post I was hoping someone had replied.
I had the same sort of problem. Turned out the head gasket was blown at the top of one cylinder and all the compression was going into the lifter valley.
I have a '72 'Cuda 340 4 speed with factory A/C and I need a white vinyl top installed.
2 questions, where is the best place to buy one and can anyone recommend a shop in the South Jersey area to install it?
Thanks