How to clean / polish instruments cluster lens?

I've had negative results with alky type cleaners as well - some tend to 'dry' the plastic and leave/produce a white residue. Post no.13 mentioned using a clear urethane. I've successfully used clears from Krylon or Duplicolor to coat well-used taillight or parking lenses - with excellent results. Totally clean parts with no waxes, silicones or lint is a must. Extra prep produces excellent results but spray should be warm - as per instructions. Cluster lenses are more 'fragile' - as being thinner and totally clear so best to use some of the previously suggested (polishing) products.