Hi seaspray,
I'm not sure about the Carr's metal black, although i think it may be similar to the Krick stuff i use.
It is an acidic chemical and needs to be used with care in a plastic dish.....i would just press out the clear plastic glazing in the ports and drop them in soloution, stir the liquid to agitate the process and when they look black enough pick them out with tweezers and rinse them off well in warm clean water.
To re fix the glazing discs i would use a clear setting adhesive like 1 hour epoxy, applied sparingly to the edge of the disc with a tooth pick.
As to the other bits of info you need i would think some of the others may have used the products. hope this helps.
Ian
