PB Transmission Removal

[pb rookie]

In the Instruction book for the New Finer Plymouth under transmission removal it states that "care should be taken to keep it in perfect alignment with the engine while removing and installing in order to avoid springing the clutch driving disc or the clutch shaft." It goes on to recommend using pilot studs, Is this necessary or will a trans jack do the job?

Also, What does "springing" mean?

Cheers!

Dave