Hi took some cleaning but the second hand unit seems to be doing its job, if you fish about on eBay there are some quite nice examples on eBay for not too much money if you get one stick a torch down the valve end and at least three of the holes if you look from the other end should be virtually clear, thats a good one, next step is get a cheap mixing bowl that will accommodate the whole valve, block the valve end up and treat it to a couple of bottles of carbon clean poured through the holes at the top you can block the valve end with a rolled up rubber glove, leave it to soak for an hour then pull the glove out and drain, next step spray a can of Mr Muscle down the holes and leave for about four hours using the remainder of the can every hour, then wash it out with hot water I did mine under the tap in the kitchen sink until the water ran clear, the Mrs wasn't impressed but I was especially when I could see torch light through 97% of the holes, last thing I got the garage to do was bung one water pipe up and pressure test it with an airline to make sure it wasn't leaking air from the water jacket, all good, as for the contaminated flywheel thats easy, saturate it in brake cleaner then hit it with a steam cleaner.
Steve.