Alright, I'm supposed to perform Mozart's Sonata no. 3 in Bb Major (K281) in a few days, and there is something that's really setting me back.
At one point there are three sets of runs, one after the other; the first one is played around a Bb Major chord, the second, an F Major (dominant) chord; and the third one returns to Bb, briefly modulates to C minor (supertonic minor), and ends around F Major (dominant).
The score tells me that they must be played staccato. These are
32nd notes.

I have been told that I must play these notes using the 'forearm' to emphasize the "staccato" sound, but I really can't play it fast as the elbow joint seems to start constricting itself for some reason. I'm thinking of instead using the wrist to help the fingers bounce on the keys to produce that staccato sound, but that's not what my teacher told me.
I am getting desperate and thoroughly annoyed about this.

What should I do?
Thank you for reading! Your advice would be well-appreciated.
P.S. in case you still haven't got what runs I'm talking about, I'm referring to the ones at 0:20 of this video, in which he doesn't even actually seem to be applying that "forearm staccato" method: