Personally I would prefer to see Luke assemble the saber on Dagobah using the Force. It made no sense to me that Luke would walk straight into Jabba’s palace with no extra training after getting his ass handed to him. He promised to return to Yoda. I’d shift the Yoda scenes to the beginning of the film, implication being that he has been training for ages before Yoda finally dies (not mid sentence after waiting for Luke to come back). Having Luke have to use the Force to assemble the saber makes Vader’s later comments about Luke’s complete skills make more sense. It’s his skills with the Force the Emperor is interested in not his skills with a screwdriver.