After the carburettor repair the tug has unfortunately developed another problem. After towing on Saturday I found a fine crack in the port exhaust manifold. This has put it out of service until it can be repaired.
I have an appointment with a CAA approved welder, near Winchester on Friday morning so if all goes to plan I will be able to refit it on Friday afternoon and hopefully it will be back in service this weekend.
Here is the picture of the crack. Notice all the white deposit which is especially marked on the shiny SS nut, it was this the alerted me to look for a crack.