GE Profile Refrigerator - Freezer Noise

Model Number: PSS26MSWASS
Brand: GE
Age: More than 10 years

Hi, up until a few months ago the refrigerator was working fine (except for the many ice maker bin auger and plastic cup issues that we all Profile owners seem to eventually encounter). This past September, the temp wasn't controlled in the refrig or freezer side and there was a buzzing sound. After observing all the ice on the back wall and behind the back wall, the repairman diagnosed a bad evaporator fan and weakening defroster. Both were replaced along with sensors. Within a couple weeks the buzzing returned. Some ice had built up again on the housing that covers the evap fan etc beneath the ice maker on the back wall. The repairman told me it had a separate issue and based off the aforementioned location of ice collecting, frozen droplets on the underside of the icemaker and bin that the ice maker was leaking and to replace it. I promptly replaced it and the issue returned after a couple weeks. Now they think it could be the water valve at the top which directly feeds the ice maker. I hate to keep dumping money into this unit because it seems like the repairman is on a goose chase replacing everything one by one. With seemingly methodical, I already have about $500 invested in these repairs and I'm getting ready to bail and embrace the buzz!

Interested in your thoughts on this. What additional troubleshooting can I do before I contact the repairman again? I always thought it could have been a defective evap fan but the repairman doesn't seem to think so. BTW, each time I experience the buzzing, the freezer is emptied and the defrosted anywhere from a few hours to overnight before troubleshooting is reinitiated.

I appreciate any and all support provided!

John