Sigma AF noise?

[CBA100]

I've got a Sigma 28-70mm f2.8 DF & I'm noticing a noise with AF & MF? It's ONLY when shooting upwards or downwards (straight horizontal shots are fine).....it's also not hindering the AF speed? Unsure how to really describe it but it's as though 2 parts of the lens barrels are rubbing against eachother.

I've recorded 2 videos, one using AF & the other in MF.......any ideas what it could be??

View: https://youtu.be/8_FlmUjfjOk

View: https://youtu.be/y8Kold204jk

 

[Dangermouse]

Sound like the gearing inside is worn and the barrel is rubbing inside, friction sounds I think.

 

[CBA100]

Sound like the gearing inside is worn and the barrel is rubbing inside, friction sounds I think.

Expensive job to repair??? There seems to be nothing wrong at the moment with the working side of it, but I suppose it's only going to get worse. The lens only cost be £60, so it may just have to be replaced.

 

[Dangermouse]

Sigma are quite good on repair prices, wouldn't hurt getting a quote