WH-3081 rain gauge

[basetman]

I have a Watson W8681-SOLAR weather station, which is a rebranded Fine Offset WH-3081.
During rainfall I kept getting lower figures than neighbouring stations.
So I did the following test:
I poured 45ml of water on the rain gauge and counted 19 bucket movements, which equals 19*0.3mm = 5.7mm of rain.
The rain gauge is 11cm long and 5cm wide, which gives a total area of 55cm2 or 0.0055m2.
As 1.0mm of rain is equivalent to 1.0L/m2, math suggests that 0.045L/0.0055m2 = 8.18mm of rain when the rain gauge only counted 5.7mm of rain.
My conclusion is that a 8.18/5.7 = 1.435 correction factor is needed to correctly measure rainfall with a WH-3081.
Can anyone confirm this?

[steve]

I agree with your calculation.

Did you pour the water in very slowly? Have you checked for problems with your gauge, e.g. debris/spiders etc, sticking reed switch?

[basetman]

I had the rain gauge cable disconnected during the test, as I didn't want to get my station data messed up.
So, I was pouring the water slowly enough to hear every bucket tip. I guess the whole procedure took about 2 minutes.
I am also sure about the water volume as I used a measuring spoon of 15ml and poured slowly 3 spoons of water.
I frequently check the gauge for debris or spiders, because when the first rainfall after a long Greek summer occurred, my station didn't measure anything... There were spider webs, which didn't allow the bucket to move...
So, this is not the case...
To be honest, I haven't checked for a sticking reed switch, but I don't have any suspicion that it has a problem...
But, even if there is a problem with the reed switch, I didn't rely on it during the test. I was just hearing the bucket tip...