[Elecraft] a little problem with tap/push menu/edit button and 'vfo knob'

[Terres Family]

Hi All,
I have been working on partially built rev a K2 (sn <1000). The 1st part
is done. If I use the 'VFO knob' to change a menu choice or a chosen
menu's setting then sometimes, often actually, tapping or holding the
menu/edit button will do nothing but if I move the 'VFO knob' just a
little bit, then often the menu/edit button will become responsive
again. Sometimes I have to move it just a little bit again. If the
menu/edit button is unresponsive then the band+ and band- buttons are
unresponsive too. If I have made successful menu or setting choices
using the band+/band- buttons (instead of the VFO Knob) then I never
lose the menu/edit button responsiveness. 
Skimmed through the trouble shooting section and didn't see this
specific problem. So far, every thing else seems ok. 
Originally got stalled when I had a defective vfo encoder but that
seemed very unlikely so it took a while before it got swapped out and
identified as the problem. The replacement encoder looked only slightly
different.  
It's not a huge deal but it doesn't seem right. 
Any thoughts?
Thanks
Jerry aa1of