The friction pads in the turntable will eventually wear and need to be replaced. This can be undertaken on a DIY basis, by your caravan dealer or a specialist company.
These stabilisers are a popular and effective method of providing confidence when towing but they do need periodic adjustment to perform at their best. They also need to be detached from the car for solo use and have to be stowed somewhere.
You also need to remember that the stabiliser may delay the onset of the caravan's overrun braking operation as the mechanism adds friction to the caravan moving forward, but the effect is slight. There can also be a load equalising affect with these spring blade stabilisers whereby some of the noseweight is transferred to the front of the towcar and the caravan axle, but again this is likely to be relatively small.
Also available are twin-blade versions to provide maximum damping for large outfits. Another variation is for the simple blade system to use a gas-filled damper instead of the conventional friction pads. Known as the Straightliner by SAS Products, this device uses an innovative V-shaped plate and roller bearing. If the caravan starts to go out of line, the gas power pushes the roller back into the centre of the V to restore straight running.
You may still see a geometric stabiliser for sale second hand or on an older car. The use of these stabilisers is not considered legal for post August 1998 (S-reg or later) cars because of type approval regulations. The geometric stabiliser relies on altering the geometry of the towing system so that the apparent hitch point is moved closer to the axle of the car. It is a clever idea that mimics systems common in heavy vehicle trailers, but without the need for an extra long drawbar. This gives much improved stability without any applied damping force. Often know as trapezium-type stabilisers after the design of the original system, various versions were produced but all based on the same concept.