Kenmore dishwasher dispenser leaking
 

I fill the rinse aid dispenser and after running a wash cycle in dishwasher, it is almost gone. Not to mention the tons of bubbles afterwards. Do I need to replace the entire dispenser assembly or just the rinse aid sensor? Thanks for any help you can give! Is this a job I can do without calling a repair man? Please let me know how to do the job.;)