It isn't really "necessary" I have seen them in absolutely terrible shape and still working just fine... However the smoother it is the better the wipers work and the slower they wear...
I think treating them with phosphoric acid and a knotted wire wheel would make quick work of em!
The acid is hard to find for us canuck's tho, and pricey to import...
If you live near
Caledon Labs they sell it, but won't ship it! They're in Georgetown (Halton Hills) Ontario
Duda diesel
phosphoric acid | biodiesel supplies
May ship it too ya from the US (that's where I got mine) Fed ex charges 15 bucks for dangerous goods handling on it!
This acid is found in Coke a Cola and Pepsi in small amounts, it's what gives them their bite!
After using it myself, I tell people about it anytime they need to get rid of rust and not metal... I bought a gallon and I've been brushing it on anything with rust, the next day the acid is gone and so is the rust. It leaves a thin coating that will protect the metal against further corrosion, until paint or oil can be applied... Sometimes I've wire wheeled and re-applyed for really rusty stuff... It's especially amazing when you can submerge the object, but that isn't necessary...
It will irritate bare skin, but washes off with water easily, it isn't anything like muric acid that stuff is nasty and will eat clean metal!
A knotted wire wheel will probably do most of the work!
Cheers and good luck if you got it apart you're well over the hump now... Those cone washers on my truck were the biggest PITA, after those everything went pretty smoothly!
