I replaced the board with the replacement board and have had no troubles for many years, I got it from BAA but I cant fin it on their site, it is the same as this one at MAD http://mad-amusements.com/product.php?id_product=737
If you decide to buy it from them they also have the grey switch covers. Just google the part number 20-9672 and you will find them at Marco, BAA, MAD even eGay
I too replaced mine but continue to have problems after awhile. Need to always recalibrate every few days 
That's weird I have only ever had to adjust it twice.
Maybe try a little bit of the lowest strength loctite made for screws to prevent it moving
