you may have a frayed or damaged shifter cable.The Woosh is about 2 months old (and we also have a 3 year old Freego)
The Woosh gear change is shockingly bad (yes even when there is no power applied)! - it feels as if there is someone at the back bashing the chain with a hammer and it's very noisy and won't always change gear
I made some minor adjustments but have also taken it to the bike shop with no improvement
Does anyone have any suggestions ?
The Freego has been faultless in this regard
give a little 1 or 2mm push on the index lever as if you were going to change to a lower gear but without committing and watch the derailleur. If the derailleur does not respond to your thumb press, then check if the outer cable sits properly and inner cable runs freely.