Please can anyone help?

Attached to my 7' wide by 6'6" steel panel Garador Mk4/22 1977, the left hand side (looking out from the garage) upper most 'inner' spring has just broken.

This spring is attached to the anchor pin at the top of the steel frame.

To remove the now detached lower spring assembly, do I have to essentially prise further apart the existing aperture in the steel frame, allowing the diameter of the 'lower' spring to pass through?

This 'lower' spring & white plastic tube assembly is rigid along its entire length.

Does this mean that the position of the prised (widened) aperture will need to be some distance from the garage floor?

Also, does this mean that the vertical length of the prised (widened) aperture in the steel frame will need to be substantial?

I apologise sincerely for the prolonged dialogue above, but not for the life of me can I work out how to remove and replace the spring assembly from within the vertical steel frame at each side of the garage door!

Candidly, must I, with great care, damage the steel frame?
Pry bars (to widen the existing aperture) and hammer (to return to the pre-existing aperture) will be the tools required?

Is the spring assembly number likely to be pressed into the inner spring 'eye' and/or the plastic collar so I know what to order?

I should like to begin the job tomorrow, Sunday 2nd August.

All information received gratefully and entirely without prejudice!
With thanks.
Kind regards,
Gary.