LT77 Gearbox Linkage

[Griff4.0]

I've fitted a reconditioned LT77 gearbox to the Griff but I'm very concerned about the linkage to the gear lever. There's an arm (about 3 inches long) with two ball sockets (one at either end) that clips over two ball ends. It seems to me that this isn't robust enough to take the strain of repeated gear changes and there must be some additional means of keeping these locked together, like a couple of clips. Can anyone advise as to what I'm missing (besides the obvious brain cells).

[RochdaleGT]

you are talking about the "classic" grifith, not the modern one?