Patricia; You will be lucky to find a supplier anywhere as a plumber's merchant, here in S.E. Surrey has advised me that the Ideal Standard Jetflow system is obsolete! Notwithstanding this fact, there is little that can go wrong with the system and certainly does not necessitate purchasing a complete new WC cistern and pan as was, at one time, suggested to me.
My "flush" suddenly gave up the ghost sixteen years after installation and, having referred to the advice given at http://www.howtomendit.com/answers.php?id=229216 as to accessing the unit, I found that it was the diaphram that had split with the result that there was no lift of water to commence the syphon of water to the WC pan.
You may be lucky and find a diaphram that 'fits' but a piece of heavy duty plastic or polythene, cut to size, operates just as well. Other than the diaphram there is little else that can break or be at fault.
Be prepared to disconnect the water supply to the cistern and the overflow - having turned-off the stop valve before attemptoing to lift the cistern off the pan and away from the wall.
You would also do well to consider new stainless steel screws (2 x 1.5 inch No 12s) and rubber washers for fixing the cistern back to the wall and a new "Do'nut" (thick rubber) washer for seating the cistern back on to the pan.
Total cost under £2.00. Total time taken 1 hour which included 30 minutes drilling out rusted wood screws, fitted by the 'professional' installer 16 years ago which had rusted away.
Gavin
October 2009