Put the new battery on, so will see how the Bus fares with this one. Super heavy duty according to the label with a 5 year guarantee.
Took the engine shroud off and had a look at the choke mechanism as it doesn't make much difference when the cold start/choke lever is pulled. Sprayed it with WD40 and checked to see if the cable was opening the mechanism on the fuel pump. Everything was OK. There was a slight rev rise when the choke lever is pulled.