Good to hear. These drives are about 93% efficient, so 260 at the wall is right. I run mine about 200 usually, and would see temps in the high 50s if it were not for sitting a 60mm PC on each. Getting them down to the mid 40s. A temperature difference that makes these LED's 3% more efficient. So cooling them is a great use of power.
The driver, when turned up, is trying to send 6.66Amps round. If it can do this with 36v worth of pushing, it's happy. 6.66 x 36 = 240w. So it's ideally suited to 240w 36v panels. Your panels won't let 6.66a flow through them without more pushing. The driver can push harder, it has 60v worth of pushing. However it's just killing itself trying to do that.
Your 180w at the wall, is about 165w of power to the LED's. So you must be demanding 4 amps through your LED's which the driver can do with 40.5v of shove. 4 x 40 = 160w. It seems you can demand anything up to 5.7A and to give you that the driver will have to push at 42v as 5.7 x 42 = 240. The problem is, the driver can be asked to provide 6.66a and try as it might, using more of it's 60v, it's just not that strong.
Anyway.. The bit you turn. Is it a plastic thing that you twist with a screwdriver? If so, I can almost guaranty that will be how your driver dies. You need a perfectly fitting screwdriver of it will get chewed up over time. These ballasts are for set&forget use. Not constantly changing them. I suggest a little investment into a ceramic or composite screwdriver of the right size. Then you won't loose it.