That was me you was helping, Thank you, any way buy 4 valves off ebay only cheap and you can blow up 4 corners it eliminates all the bags and pipe work gives you a good starting pointI was helping another member and he found that the pipe to the air tank had a hole in it were the pipe had got hot from a blow in the exhaust, it was very hard to find as with engine running you could not here it.
you should be able to take the pipe out the block and connect it to an air line to test pipe and tank.