[Yaesu] Problem with Watt meter

[David Thompson]

I have a Welz SP-122 which is exactly the same as the Yaesu YS-60 watt meter
and notice the meter no longer
is zero when I turn on the meter.  It sits at about 1/3 scale
but reads Ok when I turn on the amp.

I am looking for the manual (mostly in Japanese) and the schematic but has
anyone else had this problem with the YS-60 or Welz and can point me to fix.

Thanks in advance.

73 Dave K4JRB