Magic Trackpad Not Tracking Correctly
I have a Magic Trackpad original. Recently it has stopped tracking accurately - if I move my finger around on the trackpad, the cursor responds intermittently. I have installed new batteries, which the iMac recognises as 100% charged.
Clicking works fine. Dragging and selecting suffer the same problems as tracking (i.e., the trackpad recognises multiple fingers, but the tracking errors persist).
Now the tricky bit. If I lightly touch the aluminium at the top of the trackpad, above the glass trackpad proper, with one finger then the trackpad begins to function properly and track accurately!
It's not the iMac causing the problem - I have connected the trackpad to two other devices (2012 15" MacBook Pro; 2015 13" MacBook Pro) and the symptoms persist. I have also connected a Logictech T651 to all three computers, which works just fine.
I think that it is something to do with earthing. I have rested a small ointment jar on the same place I touch - which is heavy enough to apply similar/greater pressure than I do with my finger - and that makes no difference.