Help with herbie overflow on RSR250

[Xandernfs]

My RSR250 has been running for 4 months now and doing very well. This week the water in the overflow chamber has been fluctuating quite a bit. I first noticed it when it (overflow chamber) was very low and making noise when refilling. I adjusted and it went down again, any thoughts as to why it would be so inconsistent?

 

[Midrats]

The valve is finicky. Only make tiny adjustments. Fairly regular adjustments will be needed. It's the price we have to pay for a silent drain.