Hi all, i have just aquired a ts 400. now according to the workshop manual the disk should stop on idle, but it dont. i have adjusted the L & La scew accordingly... L=1 And adjust LA till disk stops. but all it does is cuts out. any ideas on this... also when i took the case (handle) off i can see that the carb has 3 screws not 2... wat is the third... could this carb be off an older model... i.e the H screw... thanks in advance