The decimal on D1 is wired to the output of the ripple counter, so it is suppose to switch on and off like that when the "display" button is held and you are walking. So, this tells you the input circuit is working, it is counting pulses from the mercury switch. So far so good. The problem seems to be that the 4026 counters are not counting. Check the wiring - in particular pins 1, 2 and 15 on IC3 (you know the others work if you see "00"). Also make sure the "reset" switch is open (low on pin 15 IC3).