HP 35S made in Phillipines -- new variant?

[quinreis]

I have two HP35s calculators. The first has a CN.... serial number and a poor keyboard that needs an extra hard press for some numbers/functions. The second has a PH... serial number and a much stiffer and more reliable keyboard. Inside it also has fewer screws holding down the keyboard. I suspect that the original keyboard had problems that were not successfully solved by using lots of screws, but that the Philippine factory has worked it out. So if you buy one, go for the models with a serial starting with PH... .