Topic: English Horn "E's and "A's" - Pitch - Wildness - Bocal? Instrument?

Hi folks,

I am writing as an oboist without access to an English Horn at the moment.  I've got a student with a Fossati english horn with two Fossati "Z" bocals - courtesy of the youth symphony.  Both A's and E's are very high on this instrument with both bocals; and with the 2nd octave E unplayably high.  When I attempt to correct the 2nd octave E, the pitch wildly oscillates.  I have checked the hight of the D key and this does not appear to be the issue.  My the initial thought because the issue occurs on notes which occur on one harmonic - is that this is a bocal issue.  Does anyone have any ideas?  I don't want to order a handfull of bocals to try (and have to convince the orchestra to buy) if this is not the issue.  If you do feel this is a bocal issue, do you have any that you recommend that specifically remedy this problem?

I think it's time to buy a horn of my own.

Many Thanks,