Simon, how are you connecting the computer to the mount? Whatever cable you are using for this (not counting the ST-4 cable) is what is used for pulse guiding. I think from what you say you are doing it in PC-DIRECT mode on Synscan, which is fine for using pulse guiding. Basically, just ditch the extra ST-4 cable, and turn on ASCOM pulse guiding. This has another advantage - if using EQMOD, you can also use VS-PEC with no clash with AG.
Barry, I connect the laptop to the camera via a usb cable, not sure what to call the other end. Then another cable goes from ASI camera to ST4 on the mount.
Seems that it might indeed be a PHD2.3.1 issue, the below thread is similar to my issue. I'll go bak to 2.3.0 asap since that was working so well before.
