repair or replacement of 41c clear display cover

[dmh]

Hi, I have searched the forums but have been unable to find anything about repairing or replacing the clear display cover on top of the screen (the external bit you can touch).

I'm looking for tips/advice on removing, cleaning/polishing, but probably more likely, replacing and exactly what will work (specs etc).

I've had the back off a few but not ventured to the front or display of the 41c series.

The one I have that needs work is a fullnut if it makes a difference. The clear display part is dirty and very dark in one spot and I think fixing this will help (although the display does look a bit dimmer than usual too).

TIA, dmh