Sometimes saving money will cost us more…
I have to at this time refer you to an appliance repair shop in your area. As long as you realize you are in for a service call charge at minimum + parts on your old unit.
You are right that until you know whats wrong it is difficult to purchase new. I know a decent unit sells for around 350.00. The repair of your old may be 3/4 of that, but until the service tech comes out you just do not know. So call them out and get a proposal for repair so you can make an educated decision.
The Local Plumber
Tustin, California http://www.TheLocalPlumber.com