Hi,
When moving around in the car, the seat belt becomes slightly slack and it will not retract sufficiently. However, when I disengage the seat belt lock, it tensions immediately. This is a simple, but annoying workaround!
I've lubricated the reel, but this has made little difference. Any suggestions on cause or solution please?

 

Any seat belt that will not tension correctly needs to be replaced right away. Several are offered on eBay, here in the US, as well as some tensioner repair services. Hopefully Oz has similar listings.

 

Could there be some kind of brake mechanism on the real? Have you had the the panel off so you can access it to give it a good clean and lubrication?

 

 

Thank you, I hadn't thought of that.
My confusion is that the seat belt retracts perfectly when released, but doesn't tighten back up properly when engage into the lock. This suggests that there is nothing fundamentally wrong with the retracting mechanism, but that it is not always correct on the level of tension to set?

 

Apply some silicone spray to the openings the belt passes through i.e. upper D ring, top of seat etc. It may be you have friction in locations the belt moves over when across your body but lies in another orientation when released.