Gearbox linkage issue PLZ help

[GT4PWA]

I have just had my new engine installed went to take it for a drive and my new gearbox wasn't going into 1st 2nd, 5th and reverse. we looked down in the linkages and found the following:

the peice on the gearbox linkages which controls the sideways movement to 1st 2nd 5th and reverse has come off and looks to have torn a part of it (if some1 tells me how to add photos i will). the square peice locks in between the linkages so when you pull teh gear stick to the side it pulls the selector out.

how can i fix this? does thismean the engine will need to be out again or need a whole new box?

[GT4PWA]

has anyone had this problem with the 1990 gt4 st185?