New centre shafts for TRF502X

[msxmre]

Hi i was wondering if anyone had purchased the new blue shafts for the centre of their 502X. Ipurchased these and can't seem to get the small grubscrew to go into the hole that it should once i've fitted the pin into the drive cup that then goes into the gearbox. Do i need to purchase new cups that go into the gearbox?? Looking at Lee's car it looks like he's still using the black kit ones. I may be wrong.
Thanx in advance
Scotty....