Transmission trouble?

[v30]

Hi group,
This is my first post on this group . Hope some one can help. have a 1996 cavilere throwing a code p1871. I know that the code p1870 means transmission component. and p1871 means component slipping. transnission has 78000 miles.have not towed or been ran hard . Is it possible it is a sensor gone bad or worse.? Trying to decide if it is worth taking to a mechanic or can I fix if it is a sensor? any help would be apreciated.