give johnathan wren a call and see if he can rebuild it he done a ty one for me. you might buy a 2nd hand one and it might last 5 min. his number is 01229 836038
I had the same problem with my beta phoned beta uk they told me to send the fuel cap back along with the chassis number. I bought a csp one from splatshop
still waiting on a new fuel cap from the dealer i phoned beta yesterday saying it might be the breather pipe on the frame stopping it .nope its not that hope to get time to call beta tomorrow.