Yup I'm aware of that - no good tech would diagnose a system based on pressures alone.
For a refrigerant leak: deteriorating performance over time, oil at the site of the leak (you won't spot this if the leak is inaccessible), high operating costs.
I really think first tech misguided me and wanted to sell new system. 2nd Tech did replace valve on the HOT side of the pipe. My machine is working great since the repair (30 hours).
Is there any sign I should look for?
General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"