whirlpool dishwasher adp4601

please help! weve owned the above mentioned dishwasher for a long time now and it has always worked perfectly untill recently! we noticed a puddle on the floor after the machine had stopped and after removing the plate from underneath i traced the leak to a hose and repaired it. the machine worked fine for 2 loads and then the next time it was turned on it stopped 2 mins later and the power light was flashing 4 times repeatedly! i found this forum after a quick net search and traced the fault code to “no drain detected” the drain switch gate was not gunged up and im sure the drain pump is working (i poured a pint of water down the bottom of the machine) so it seemed to be a faulty drain switch which i orderd from ukw. the new switch arrived and i promptly fitted it! the machine worked perfectly for 1 wash but has now stopped again and have the dreaded 4 flashes! please help im stuck!