Well, it turns out that the banding I was getting on the images wasn’t due to reflections from the metal guide rail. I totally dismantled the scanner, bought some matt black spray paint and gave the inside of the scanner a good going over. This involved removing the sprung cable that drives the scanning head, masking off the electronics (which are glued in place it seems), going outside when the weather was good and spraying it all to hell :-)
Anyway, I put it all back together and… I’m still getting the streaks. I’ve put black tape all over the metal scanning head to prevent reflections but still, I get streaked images. From this, I surmised that I’d some how managed to damage the sensor itself, most likely from handling it too roughly. Oh well, the scanner didn’t cost me very much, so I’d look out for another on ebay and use the sensor from that and all should be well.
So I got hold of another scanner (£10 this time!) and this weekend I dismantled it and put the sensor into the old scanner. Fire it up and… streaks. Dammit. I now think that the streaks are caused by my less than accurate modification of the plastic sensor housing - when I ground it down in to shape - I wasn’t terribly consistent. I think now that the streaking is due to part of the sensor housing letting more light in - throwing off the exposure.
I now have two options - grind down the already modified housing to try and even it out. Hopefully this will give a more consistent image. Option two is to modify the new housing in a more accurate manner - I’m thinking using a fine modelling saw and knife rather than grinding.
Grinding is really messy so requires working outside and nice weather - which I don’t expect much of as we enter October. But I’m loathe to hack at the new housing in case that isn’t the problem…