Good idea! Just find a similar tuner cover. Send it to GAD, he can engrave GUILD on it, (it'll give him something to do when he's bored in the middle of the night).
Why are there scratches on the body of the tuner?
Did YOU rempve the cap? Or did it fall off and got lost?
Is the gear damaged? - could you take new parts from other Schaller tuner?
pm sent.I have some of those as singles of still needed. Have a complete set with tags for future reference too.