Toyota Camry 2000, 65K Miles, transmission slips when in rev

Toyota Camry 2000, 65K Miles, transmission slips when in reverse have been told I have an oiling problem.?
When cold it works perfect in reverse with no slippage, after warm up when put in reverse transmission slips, can this be fixed easily, the transmission shifts perfectly going forward.

may be many problems:
loose band inside tranny,
reverse silonoid not functioning properly to build up enough liquid pressure,
burt gear plate,

doing many reverse doughnuts lately?

Changing the filter and having the transmition flushed may help.

try draining the transmission liquid and refill with new liquid. more if the liquid in the tranny is blackish and smells burnt. if this didn't crack the problem, rebuilding the tranny may be the answer. but for me, may also replace the tranny. resources may be the junk shop. here in our place, we can get used car parts which when cleaned of external seems new. like now, I just got a relay panel for my AE92 corolla. got it cheap.