One suggestion. Cover most of the jar with foil, leaving a small opening for the sensor LEDs to peek out. This minimizes the jar acting like a mini-greenhouse and unnecessarily heating up the electronics.

I also use a Redrok controller on my polar axis tracker with concentrator, although a different model than yours. It has four LEDs and is all surface mount.  Contrary to TomW's experience, it has worked flawlessly and is quite accurate - I'd guess within 1-2 degrees. I think it's a bargin. It's kinda neat watching it seek out the brightest part of the sky when the clouds are floating about. It often is not where the sun is, depending on cloud fringing effects.