Hi
SimRice,Here are my observations for you:
(1) the engine driven sprocket (the small one) is unserviceable and will need to be replaced as will the primary chain.All other sprockets appear serviceable.
(2) Re: the drum weight in your rear roller, please read the complete thread
HERE for the explanation.

(3) The brass bush was original manufacture; the end-caps were replaced by plastic in the Series 2 Scotty Model 45.
(4) The reel has plenty of life in it, but will need a spin-grind. The bed-knife however may need to be replaced....please ask you engineer/machinist who does the reel grind his opinion.
As you are going to do a restore on your machine, I will shift this thread to the Restoration forum topic.