T-Wah's with the Silver Screw are quite common. I've got one myself (the model with the 't' under the 'w' of Wah in the logo).
This one has the last version of the T-Wah logo on it and is probably original but maybe one of the last that they put a Silver screw on. It's not unfeasible that the bottom plate with the 'unscrew using your fingers' text on it is original too. I think there was a transitional period where plastic thumbscrew pedals had the 'use a coin' text sticker on them and vice versa.
It would be interesting to find out the Serial number of this pedal though to establish when it was made as I think Bossarea is compiling a chronology of the early pedals.
That looks like a nice clean example of a TW-1 too!