Thanks I've done some searching now on leafield c7 valves and found a few helpful how too's.
I cant seem to find anywhere close to me that sells the wrech or factory spanner.
I'm going to try by hand first as you suggest with a rubber glove for grip.
If not a call to leafield marine on monday and see if they will sell me a tool.
Funny thing is the tubes hold air perfectly and I have not had to top them up, If I had not heard the sizzle I would not have known they were leaking, I am thinking they Maybe over inflated.