HDG track and hold issues

Hey guys,Only started having issues with this lately. When you dial in a heading it tracks to within a degree or so of it. After dialling in a few different heading the offset seems to get larger.So first time you dial in say 139, it might track to 140 then after dialing in a few more you could dial 90 and it might track to 92. Seems to be always 1 or 2 higher.This has me baffled. Tried all different fsuipc setting, and fsuipc settings off. FSX default weather and ASE. The offset seems to be magnified in ASE for whatever reason but still the default FSX weather presents a problem.Any ideas would be welcomed as I'm clueless at this stage.Thanks,Mark.SORRY,,,this was supposed to be posted in the default 747, not the 748. I'll repost there so this can be deleted. Sorry again.