Regarding getting a replacement screen, there is a company called BBA Reman (
http://www.bba-reman.com/gb/index.aspx) who offer this service. There may be others which other forum members might know about.
About the only other issue I'm aware of is the milometer display fading or failing elements in the display, which strangely enough seems to be affected by heat. I replaced mine a few years back because the pixels were failing in the on position, so producing a 'blob' of light, which over time covered more and more of the display. The replacement one is fine in that respect, but one side starts to fade if I've been in the car for several hours.
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2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts
My DIY jobs -
Replaced alarm horn,
Replaced Coolant Temp sensor,
Updated RNS-D firmware,
Installed Reversing Camera and Digital TV,
Dashcam Installation,
Retrofitted Rear Blinds,
Auto-Dimming Rear View Mirror,
Chrome Boot Struts
Sold! 
2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights
My DIY jobs -
Fan Jet Windscreen Washers,
Retrofitted Electric Side Blinds