300 tdi timing belt walking off pulley

96 300 tdi
In the middle of changing timing belt ,old belt of unknown milage but I've done 7k in her
Old belt was running off timing pulley and wearing away at the belt (Glad I'm changing that I thought ) Engine had the newer pulley kit with the modified pulley fitted

I've fitted the same ,tensioned the belt to 8-10ftlbs and followed the procedure of tensioning belt twice and rotating engine twice

Rotate the engine 4 plus times and you can see the new belt trying to walk off pump pulley ?

Looked online and one thing that came up was the bolts / bushes that hold the rear of pump to the steel bracket (bushes were seized in the holes so I opened up the holes in the bracket so they now move freely)

In having a coffee now and will try again to tension the belt and see what happens

Any suggestions?

Thanks
Chris

Timing case

Just read this. How did you get on?
My thoughts are: are tensioner pulleys sat flat and square with no muck or burr under them? Crankshaft oil seal not seated in housing fully and so crankshaft pulley standing out a fraction?