Milwaukee mc510 orp meter jumping

[scotty333]

Guys
I’ve just set up my orp meter and I’ve got the probe in the weir where it’s dark and has steady flow over it
Trouble is , the readings depending on how I hold the unit jump around erratically
Any ideas?

 

[Gumbies R Us]

Bumping your post!

 

[scotty333]

Thanks but it’s settled now at around 340mv