Ok Been having a read of this thread and on the web in general on this issue.
The rattle on start-up is caused by the engine oil draining out of the Variator.
Why does the oil drain out the Variator? see Post 57 above by Phil.
To be fair its most likely to be the solenoids at fault causing the problem. (Oil Solenoids)
Which makes sense, the oil leaks out from the variator through the Oil solenoid control valve when the engine is stopped, worn internal sealing probably, and one or two threads comment on oil leaking out the top on the Oil solenoid valve indicating internal leakage.
The loss of oil internally in the Variator, over the long term, will cause machanical damage, and likely damage the locking pin. Mechanical noise is bad? If not designed to take it. Which the variator is not.
The NRV valve fitted to the cam cover modification, is a back up to the loss of oil through leakage from the Oil solenoids. This is my understand.
Since the cars left the factory without oil draining back from the Variator, and the oil is fed from the Cam bearing supply through the oil solenoid to position the Variator in the correct position for the rev range, power etc. The Oil solenoid would appear to be the likely suspect.
Has any one just changed the oil solenods