I asked some while ago if these things might include a clutch to
prevent overload, because the drive was frequently slipping and
received no answer. It is the 600w model, with a blade able to be
rotated from H to V cut.

I have been inside and no, there is no clutch at all. The slippage was
due to a worn drive system.. The end of the motor shaft has a pinion,
which drives crown wheel, which was partially supported on one side by
a casting. The quite soft metal crown wheel had worn in one spot, which
was where it was causing slipping. The crown wheel was on a spindle,
with a small roller bearing top and bottom, bottom in rigid casting,
top bearing supported by the plastic housing. Absolutely no adjustment
anywhere at all and a very poor design.

I fitted a small washer under the bottom bearing, to push the crown
wheel a tad further out of the casting, making the crown wheel a
tighter fit against the motor pinion. It will not likely last long.

I have had it around three years, during which time have have probably
cut our bit of hedge around nine times in total, so rather disappointed
that it survived such a short time.