Get it aligned exactly onto 28E, then nudge the dish round a few mm at a time until you start to lose 28E, then switch over to your 26E tp, and keep going. Its a faff as 26E isnt that strong in the uk. It took me over an hour last time I tried moving my big dish onto it. If you are getting 80-90% signal quality chances are you are picking up 28E. My receiver was giving signals with around 50% quality on that tp.
Once word gets round Eri is showing footy, wonder how long it will be before they are pressurised into switching it off.