I have a problem with my Heathkit ID-4001 Weather Station. The wind
speed works fine if there is any wind but when there is a calm wind
condition it occasionally starts giving erratic wind speeds. If it
should be reading zero speed, it reads zero and then jumps to a higher
wind speed, such as 32 and then back down to zero or up to 41. There
doesn't seem to be any pattern that I can discern. The actual wind
speed values tend to be random and when they occur appears to be random.
It can go for some time sitting at zero and then give an erroneous
reading or several erroneous readings in quick succession and then set
at zero for an another period of time. As soon the wind picks up it
appears to read the wind speed flawlessly.

Any ideas on what the problem might be or what to check for?

Thanks.