Originally Posted by avern1

You need to find yourself aa new mechanic. The reason for the sudden loss of reverse is that they removed the wrong plug when they drained the transmission and they have released the mounting for the reverse band.
The following is a quote from the JATCO tech manual.
I quote verbatim from a technical bulletin regarding the JATCO JF506E transmission: 'A no reverse condition after fluid service: This could be caused by mistaking the reduction-band bolt for the fluid check plug. This mistake is easily made but the consequences are time-consuming and expensive. Once the reduction-band anchor is removed, the band will move out of place, which causes the transmission to seriously slip in forward gear and to lose reverse."..