Thermador Professional not cooling. obvious problems already checked.

Hi all, I've seen similar questions asked and answered and have been able to rule out some of the most common issues.

unit is the:thermador Professional KBUIT4860-A02

it was purchased in 2005, so beyond all warranties

I replaced the compressor relay about 2 years ago. I was able to diagnose and repair myself thanks to this page, so thanks!

current situation:

on easter, while preparing dinner for family, I noticed items in the freezer were no longer frozen, temp said 36 on display, fridge was at 40. So both were warmer than set.

I emptied the freezer and left food in fridge and it was able to maintain 40-44 for 24 hours. Once i had enough space to empty it out, I turned it off.

I checked the condenser coils, little dusty, but not bad. I cleaned them to perfectly clean

condenser fan is running

compressor is running. I can hear the relay tick and can feel the compressor run and get hot.

I disassembled the freezer to check the evap coils and fan. Evap fan was running and no ice or frost was present. I can feel airflow in both freezer side and fridge side

I replaced the compressor start capacitor because i had a brand new one laying around from the last time I was diagnosing.

I let the fridge sit a couple days because I was busy with work. Last night I turned the fridge on and left it overnight. using a laser thermometer, I found that the freezer was able to lower the interior temp by about 3 degrees in 14 hours.

After running for 14 hours, the condenser coils were not even warm to the touch and the evap coils were exactly 72 degrees.

from what I can tell the compressor is running non stop though I'm sure it cuts off periodically to cool off.

I checked the resistance of the compressor with an ohm meter and seemed fine

used an amperage meter on the wires going to the compressor and there was current flowing

Okay, so what is left? from what I've read, here are my options

Refrigerant - Wouldn't this explain why the condenser coils are not getting hot at all even with the compressor running for 14 hours and still explain 3 degrees of cooling?

My system is a closed system so a leak is unlikely, but I understand it's fairly easy to add R134a, they have 12oz cans plus a piercing tap and hose for under 40 bucks on Amazon

Am I correct to rule out the Thermister and Temp Control Thermostat since the fridge and freezer are trying to cool and maintained lower temps initially? also because the temp display inside seems to be accurate?

Temp Control board and Main Control Board are the last things that it could be I guess. as these are the most expensive, Im hoping this is not the problem.

I would greatly appreciate anyone's opinion. Please let me know if I missed anything and let me know what your thoughts are on my situation. I'm a pretty handy DIYer and would love to get this fixed myself.

Thank you,

-Michael