Cobra m56spb gearbox spring

[JamesBenstead]

I've got a problem with my Cobra mower the drive belt for the rear wheels came off and now won't stay on. The pulley on the rear axle gearbox just flops over and the belt falls off. I've googled it found an exploded diagram and I think I'm missing a spring that pulls it to the back but I can't see where it hooks onto. Andybody got a picture or suggestion, please?

[Mick]

Hi James, and welcome to TGMForum.

Yes you will need the spring, and it's likely fallen off when the belt came off.

You might be really lucky and find it hanging just in front off the gearbox, or laying on the lawn.  But you'll no doubt see from the parts diagram that the spring has one hook facing forward, and other hook facing backwards.

The bottom of the spring hooks in a hole under the front of the gearbox, and the top hooks on to the deck just in front of the gearbox.

Spring is this one, (sadly out of stock here), but to give you an example. https://www.gardenhirespares.co.uk/genuine-cobra-gearbox-tension-spring-26801114901.html

The belts on the Cobra's tend to come off when the belt cover gets full of grass.  A good clean out should prevent it from happening again, also check there's no bits of twig stuck in either of the pulleys.