I have a JVC HR-VP644U VCR (couldn't find any online manuals or database
entries for it) which has the following problem: Once a tape is in,
everything works fine. However, the tape won't eject if it's in, and if
it's out, the VCR doesn't recognize when I feed it one. If the tape is
(manually) loaded and I press eject, the tape will unload, pause, reload to
play position, and then turn off. I can turn the VCR on and use it just
fine. I have opened the machine up and can't find anything obviously
wrong--no broken pieces, dry belts, broken teeth, etc. I notice that the
switch on the side of the cassette carriage which is activated when I load a
tape doesn't seem to do anything, but I can't prove that it's broken.

Can anyone suggest a likely cause, mechanical or electronic? Would a new
cassette carriage likely fix this? After a lot of looking around and etc, I
wonder if there might be a catch in the portion of the idler mechanism that
is supposed to unload the tape. I can manually cycle the tape in and out,
but when I press the eject button, I wonder if the second half of the eject
action is either not getting triggered, or is not engaging.

Many thanks in advance.
dmn