Hi,Welcome to Just Answer, My name is XXXXX XXXXX forward to helping you today.
What happens eventually on these is the little dirt and grit gets inside the valve itself and clogs set up so they no longer open, you can't really take these valves apart and fix them it would need to be replaced, the valve is the part the hoses connect to and it's electronic, you can order one of these at the following link,
http://www.repairclinic.com/PartDetail/Water-Inlet-Valve/205613/3440?modelNumber=LA512 it's just time to replace it that's all, hope this helps, thanks, Bryan
Do I need to call someone to do this or could we install this part ourselves?
Thank you! Wendy