Greetings Arthur,
I note that you have been advised that the lockup clutch is jamming because some of the lining has flaked off to jam it and that therefore a transmission change is inevitable. A costly first off analysis. Logically would a jammed clutch consistently clear, in the way you have described?
Lock up operation is controlled by solenoid valve “B” which is a normally closed, and is opened to drain at a 95% duty cycle in order to fully engage lock up. Lock up release occurs when the solenoid valve receives a duty cycle of 5% or less, whereupon the valve is closed to drain and full lock up release pressure is applied.
Control of the solenoid is dependent on the TCU and when in first gear or reverse, i.e. when you are getting a shudder, the solenoid should receive a only a 5% pulse modulated duty cycle and there should be no lock up.
As you start with a lock up condition this could be due to solenoid “B” not closing properly or having a worn or fouled seat, any leak to be overridden immediately full transmission line pressure is available.
The solenoid could well record a fault code at start up and you should first off run a test. However the test should not be taken as definitive as the system has limitations which depend on solenoid armature movement and the electrical circuit both of which may be OK.
Importantly the solenoid involved is accessible without removing the transmission, being part of the valve body. The message I have is to investigate fully before writing off the transmission.
Trevor.