thanks but ...
fraggle, thanks for the advice which i have just read. unfortunately i had already started playing with some of the complicated bits. fortunately i seem to be making some progress - while also creating new probs. flushing mechanism seems to be working fine and i cleaned all that out. then by taking the fill mechanism apart and putting it back together, a simple adjustment to one of the connections where water was trickling seems to have created really good water flow to refill the cistern. however, the cistern is not only filling quickly, but it now isnt stopping filling and just reaching the top of the flushing mechanism and overflowing into the toilet from the top of that. there isnt a traditional ballcock that can be set to top the cistern filling so not sure where to turn next. any ideas?