The gear-change mechanism, including the selector forks and the other parts of the assembly will, sooner or later, require some remedial work to ensure that the gear-change is accurate and nicely 'snappy' rather than hit and miss with a sloppy, imprecise action. The more parts you can afford to replace with new zero wear items, the better, ultimately, the results will be.
This component and some of those listed below will give you an idea of what maybe required for a satisfactory outcome:
Try this gasket sealant: 08C70K0234M used by engine building professionals. Add as many items as you wish to the same shopping cart, new shift shaft 2541126D01 retainer 2474121A00 bearings 0926225006 & pins 0422104089 for example, and still only pay the same single fixed price shipping cost. This component will almost certainly have other applications within the Suzuki model range; so, please check the part-number is right for your machine prior to ordering?