Five years and Luke hasn't gotten his hand fixed yet?
He never gets his hand fixed, that’s why it’s a bare-metal robot hand in TROS.
2 fun facts:
1) I guess they didn’t want to pay to CGI Luke’s robot hand in TROS because he never uses his right hand and you never actually see his right hand (he keeps it down between his robes and cloak the entire time).
2) Mark Hamill is actually left handed, so it makes sense that he catches his lightsaber and raises his x-wing with his left hand.