Your 600 series ford tractor clutch does not engage?

check the back axle oil level first as if it is low the dual power can slip

then check the free play on the clutch pedal you should have between 1cm an 2cm of free play in the pedal before you feel pressure on the pedal

if there is no free play then adjust the linkage under the cab until you have the desired amount

if this is not the problem your clutch is probably gone you will have to split the tractor

and examine the clutch and pressure plate and repair as necessary

if the clutch is good then you could have a dual power problem so the dual-power unit will have to be checked and repaired