When you say fiddle do you mean with the cable at the PS/2 connection? The port itself could be at fault.
If you have USB ports you can get an USB-PS/2 adapter to connect the mouse (and keyboard).
Surface Pro (2017) vs Surface Pro 4
20 groundbreaking 3D animation techniques
How to mine Bitcoin on Mac
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.