I have an older dishwasher also and recently my wife alsocomplained about it not cleaning right... so me being the man I am tried invain to clean the things... Bought new spray arms online and installed them inminutes...now the thing works like new... However I have also found that if theheating element goes bad then that also can mess things up bad... So I wouldbuy new spray arms, and also check out the heating element to make sure it isworking... Here is a tip that will help you with the online buying...
Dishwasher Spray Arms not Spinning
How to Buy Appliance Parts Online
A bad heating element causes many problems in dishwashers...
Dishwasher Problems The Heating Element not WorkingDishwasher Maintenance
Asker's Testimonial " explanation very clear. will give it a go and seehowsimple it was. thanks Ronnie " - ronnieshomes