The MBP is 8GB and runs Sierra, current version, and is an i5. 15.4" model. The trackpad seems to be having serious mental issues. If I try to move the pointer it either barely moves or jerks all over, and clicking doesn't always work where the pointer seems to be. (For example, I can click the Safari icon and it will open Finder instead. With a mouse attached, it still is jerky but it is usable. I have no idea how to troubleshoot this or what may be wrong. There is no visible damage to it. Could it be a matter of just needing to clean the surface with a moist and soapy (alcohol?) towelette? I've tried resetting PRAM and I even upgraded the OS from El Capitan to see if something got hosed at the OS level. No good. Ideas?