Mine's a bent shaft. I guess only Victa agents can replace/repair the centrifugal clutch or internal broken cable?

with out a make and model it is hard
suggestions are
broken cable if bent shaft
centrifugal clutch failure

broken drive cable if bent shaft
centrifugal clutch worn out or oily

could be the centrifugal clutch or id a bent shaft a broken cable inside

the problem will be in the cable if bent shaft or in the centrifugal clutch
the head comes off after you remove the locating bolt and loosen the clamp bolt and the drive cable /shaft will slide out

with trimmers , there is a shaft or as in a bent shaft a cable that has square drives and ends
these can become oval or break off if continual heavy loads are applied to the cutter head
next there is a centrifugal clutch at the top of the shaft and if continually used in heavy work that clutch will wear out and not grip sufficiently to drive the shaft
most cutter heads do not suffer problems other than to get loose and work down the tube thereby allowing the square drives to part

remove the head from the shaft( tube) and remove the broken drive cable
get and fit new cable and then reattach the head to the shaft ( tube )
the gears in the head are fairly robust but the drive is a cable which twists up and pulls out of the drive squares at either end

On your bike there are two clutch parts that can wear and cause this problem. The broken spring should be replaced but is not causing the problem. Check the bottom of the clutch release shaft #13102. The end of the shaft may be broken, bent or severely worn. The part the shaft engages with is the clutch rod #46102. It could be bent, broken or severely worn. This part is inside the clutch hub. Just remove the five springs and then the outer cover plate and the rod should be accessible.

Here are the possibilities > > Bent clutch push rod, missing push rod ball bearing or push rod, worn out actuator shaft cam, Missing friction disk (5), or pressure plate (4), totally worn out friction disks, clutch plates not installed in the correct sequence, extremely weak clutch springs, stripped teeth on the clutch hub, wrong clutch cable length (inner cable vs outer cable), broken shaft, bent then broken shift fork stems, broken slider gear dogs and a missing shift fork pin.

You didn't say if anyone had worked on the clutch or gearbox so I am throwing in nearly EVERYTHING possible that could create the problem. A little more background and most of the above can be ruled out. Get back to us.

Okay hotcrap10, since the fellow who did the original posting is not responding to clairification requests, I hereby turn this posting over to you. ( sounds official don't it! ).

Here are the possibilities > > Bent clutch push rod, missing push rod ball bearing or push rod, worn out actuator shaft cam, Missing friction disk (5), or pressure plate (4), totally worn out friction disks, clutch plates not installed in the correct sequence, extremely weak clutch springs, stripped teeth on the clutch hub, wrong clutch cable length (inner cable vs outer cable), broken shaft, bent then broken shift fork stems, broken slider gear dogs and a missing shift fork pin.

You didn't say if anyone had worked on the clutch or gearbox so I am throwing in nearly EVERYTHING possible that could create the problem. A little more background and most of the above can be ruled out. What kind of oil do you have in the gearbox? Did you take the clutch apart? What else can you tell me? Get back to me.