[Vwdiesel] 81 Rabbit pickup fork in transmission?

[Dave Heart]

No, not a dinner fork....After doing a shifter adjustment  mechanic claimed a fork in transmission is cause of shifter not always going into reverse. Doesnt always completely engage reverse gear, instead get a clashing sound and have to retry putting back in gear. once in awhile 1st gear pos out when starting out... Lately the reverse issue has been getting worse. Comments please....Also would changing the standard xmsn fluid to MTL help in this case? Tx in advance....