I have an old LG that has been a good unit .It

I have an old LG that has been a good unit .It started cutting off after only running a few minutes .I took the face plate off and found gunk on the grill .So I took a brush and cleaned it up . Im just a older lady who likes her unit . I think a sensor must be on the fritz its LD40Y5 . Im thinking of taking the top off and seeing if there is gunk under there .What do you think ? Is it time for the bone yard ?
thanx caroline