star trek - ST: First Contact: how did the crew get back to the future having destroyed the main deflector?

In the film First Contact, when in the past, the Borg from the future try to contact the Borg in the past's time period by building a transmitter out of the particle emitter on the main deflector dish. The particle emitter is detached from the deflector dish by Worf, Picard and Lieutenant Sean Hawk, and then blown up, to stop the Borg transmitting their message.

Now, fast forward to the end of the film - the crew of the Enterprise have to get back to the future, so Picard instructs whoever it is on the bridge to emit a reproduction of the inverse tachion pulse that opened the temporal vortex that the Borg sphere & the Enterprise went through to get back to the past at the near-beginning of the film.

My question is: With the particle emitter on the main deflector dish destroyed, how exactly did they emit this pulse? Do they carry spare particle emitters on board (doubtful - it's a pretty large piece of equipment to carry spares for), or did they construct a new one somehow? Or do they have a secondary deflector dish powerful enough to do the job? Or is it just a gaping plot hole?...

Answer

I realize there's an accepted answer to this -- but the dialog in the last moments of the movie contains an answer to this which is apparently being overlooked.

They don't need the deflector dish; they modify the warp field to generate the chronometric particles.

PICARD: Report.

WORF: The moon's gravitational field obscured our warp signature. The Vulcans did not detect us.

LAFORGE: Captain, I've reconfigured our warp field to match the chronometric readings of the Borg sphere.

PICARD: Recreate the vortex, Commander.

LAFORGE: Aye sir.

RIKER: All decks report ready.

DATA: Helm standing by.

PICARD: Mister Data, lay in a course for the twenty-fourth century. I suspect our future is there waiting for us.

DATA (OC): Course laid in, sir.

PICARD: Make it so.

Typically the deflector dish is the "Do Impossible Stuff" fixture on the ship, but in this instance they don't claim to even need it.