!st and Reverse issue (manual)

What is your question?

At 90 k miles, 1st and reverse gear (especially reverse ) require extreme force to be geared into. What possible fixes or adjustments or possible? Price range for such? A mechanic told me the clutch is fine and that it is likely to be the gearbox. He reccomended taking it to the dealer, since they might be able to do a tuning (synchronizing?) as oppose to a full replacements. An thoughts. Thankyou