Bought Troy Built Pressure washer (2550 PSI) 13 months ago. Has worked perfectly up until now. This time, the water comes out when you pull the trigger, but it's got the pressure of a garden hose at best.

We have kept this in the garage and it has only been used 5-6 times. Never put any bleach (or any chemicals at all)in it. The box store were we bought it says it is probably the pump and it would be cheaper to replace the pressure washer than to fix the pump(of course). Any ideas? Any chance it's something other than the pump?