Reply to "ZF won't shift when cold?"

Certainly could. The stock clutch release distance was marginal when the car was new, so after normal wear 'n tear on the linkage & hydraulics, clutch drag when shifting causes synchro wear with each shift. Plus, nobody ever mats the clutch pedal when shifting, so that just increases the drag on clutch and synchros. This is why its SO important to install a long-throw slave cylinder in your Pantera or Mangusta, to get more disengagement distance in your clutch. Shifting slow and deliberate will prolong what amount of synchro life your car has left, but nothing can replace missing metal.
To help shifting now, center the gearshift lever according to the detailed instructions in your Red Owners Manual. This may help some cars shift easier. And removing the secondary shift-detent behind the shift stick also eases shifting. For those unaware, remove the shifter surround trim and chrome gate. You'll see a snap-ring behind the stick. Remove the snap-ring, the sheet plug, a spring and the cylindrical detent, by sticking a finger inside and pulling it out. Cork up the resulting hole with duct tape or something to keep dust out, and replace the trim. Thats it. Shifting will definitely be easier. Theory is, the ZF already has shift-detents inside the cases so this one is not needed. The fix is so simple, most vendors do this to customer cars free of charge.