Filing wiper spindle to use Series III adapters

[IIA]

I'd like to file a flat spot on the spindles on my Series IIA wiper spindles so I can use the newer adaptors. I've never filed metal before and it looks like there are a zillion types of files out there. Does anyone know what the spindles are made of (stainless? aluminum?) and what type of file I should get? Also, can I get away with doing this operation without removing the spindles from the windscreen?

[deezgunz]

I have a series 3 spindle that you can have. Its bent but after investigating it perhaps it will fit in a IIA? As far as filing I'm sure it can be done...even with them installed. File it with any medium file (I don't know the difference in a bastard file etc...I use the same one I sharpen my chainsaw with) or dremel it. finish it off and deburr the part with some wet sanding sand paper or a fine file. I recommend staying with the stock units.