Re: clutch slipping
Gearbox synchros are the parts of the gearbox that basically use resistance applied by the gearchange itself to speed up the lower gear to match the speed of the output shaft to make a smooth downshift.
Basically they make a whirring noise when doing this, sounds a bit like "UUUuuuuummmmmm".
Or at least thats what they sound like when they are doing their job.
If they play up it can be tricky to get into gear.
Has your problem ever happened in another gear besides 2nd, if so then its probably not this.
I just brought this up because you mentioned a whirring noise.
I thought a clutch slipping noise would sound like increased revs but no acceleration.
I personally don't know if there is a whirring noise associated with it,
somebody else might be able to comment.
I'm not a doctor - but I really do recommend braking later