John, up at JDGrandt Strings, can also rescale your problem strings for you. Sending in measurements of the hitch to forward bridge-pin and then the speaking length, will allow a change in the scaling to help prevent your breakage problem. Their website explains the information needed.
There are many reasons for strings breaking, however.
1. Angle; If you are wrapping the strings too high, and the tuning pins are sitting too far above the bearing bar, the angle can be too much for the string to handle. POP! Make sure you are giving the tuning pins the correct height, before putting the new coil/string in place. Likewise; too low can be a problem, if there is only a bearing pin in the plate. Match the neighbors!
2. Bearing; Nicks on the upper plate bearing pin or bearing bar can also bind the string and load that upper segment too far.
3. Excessive twist; Sometimes we get too aggressive on putting a tightening twist on the bass wraps. All you need is a twist or so...I only put a twist in the direction of the wraps until I feel resistance and stop. This is rarely more than 1 to 1.5. More can cause problems and lead to breakage or a dull-sounding string.
I don't generally find a breakage problem in Wurlies. They are a solid and reliable instrument, in general. Take a hard look at the string/pin heights, and the wear on the bearing points. Otherwise....do consider a minor change in the scaling to reduce breaking strain on those wires.
Not a saleman,
but their strings,
have helped me!
Jeffrey T. Hickey, RPT
Oregon Coast Piano Services