i would remove centre consol ,rubber gaiter etc ,2 x large phillips screws on tin cover around lower gear stick, you will see 2 x spirng either side of gear stick these springs should hold gear stick in 3rd 4th gear aligment ,betwwen springs is a plate holding them in position it often breaks off bottom plate and can be rewelded on or replaced its held by 4 x bolts 2 of which also hold springs ,this plate has slotted holes to allow movement for adjustment gear stick wiil naturally go over for 1st 2nd and 5th and rev but needs springs for 3rd 4th,underneath top housing gear stick goes into selector yoke this can come loose on grub screw or ball but i would think bias plate