After a period of monitoring our rain statistics I recently came to the conclusion that we were under reporting rainfall against other official & unofficial stations in near proximity. After pullling the station down for a look & checking it was clean & level etc and measuring how much water it was taking to tip each bucket found one bucket was very slow in comparison to the other side. I have since used the screws under the buckets to rectify this and will see how this goes. As far as I can tell each tip should occur at 4.28ml per 0.2mm. Am I way off?? Anyone else have other ideas??

Yes I could have used the software to offset it. But the error I was finding was a bit higher than 5% it was more like 13% or there abouts which in my investigations is also well documented. I would prefer though the buckets worked consistently which is why I altered the screws but its a bit of a time consuming process. I even had to take the metric converter out to get enough adjustment.