Speedo Drive 5 speed box worm gear

[ultimaguy]

Can anyone help with advice or diagrams of worm gear speedo drive in a 2001 1.6 Roadsport 5 speed box. Output gear on tailshaft of gearbox does not rotate when propshaft is turned, is this an engine out job or is there any other way, can caterham speedo with digital odd be used with a different speed sender. Please Help