Hi Sam
I would check both gear change bushes. Im assuming you have an R4gtl. One is located in the cross member which straddles and is bolted to the inner wings. The gear change rod passes through the center of the crossmember. There is one bush there. The other bush is located at the very end of the gear change rod in the circular end piece. This connects to the rod which protrudes in an upwards direction from the top of the gearbox. Both are prone to wear. In addition, there are two gear change springs which break/come adrift. One is located at the bulkhead end and is attached to the gear change rod via a large black circular piece of plastic. The spring hooks to the rocker cover at the other end. The second gear change spring is attached to the rod which protrudes from the top of the gearbox. There is a little circular hooking point on the rod. The spring is hooked at the other end to a flat metal supporting bar which is bolted to the cross member at one end and the subframe at the other end. If the bushes and springs are in good shape and in situ you should have a firm and responsive gear change.
Best Wishes