2nd gear stutter.

[Fazerider]

I'm surprised there aren't nasty noises if the gears themselves are damaged, but if that is the case it's not a long job to take the sump off. Not that that'll give you access to the cogs to change them, but there will be teeth lying at the bottom of the sump.
(If so, a new motor is the simplest solution unless you're keen on taking things to bits for the experience.)