As this project continues (drags on).. I disovered that the bottom large
board swings out, so there is fairly good visual access to the bottom of the
transport mechanism, after the Servo/Syscon board is also swung out of the
way.

With the top and bottom covers off, and the unit standing up on it's right
side (facing the front), the bottom board is attached to hinged signal
connectors, so it can swing down to the benchtop after 2 screws are removed.
Then the Servo/Syscon board directly under the mechanism can be unlatched
and swung down after removing 1 screw, and releasing the capstan motor
harness from the plastic anchor.

It may be necessary to connect some temporary jumpers from the pads where
the removed screws would ground the boards, to the chassis, in order for the
board grounds to be maintained.
I thought I had them both grounded properly, but the key funtions (FF, Rew
etc) didn't work while I had the boards dropped down.
However, Eject did work smoothly a few times, without floundering.

After this initial test, I put the boards back in place with the screws, and
tested cassette loading and numerous Eject cycles without any problems.

With a little more manipulation, the ribbon cable in the corner of the
Servo/Syscon board can be coaxed to come out of the corner where it's folded
over, so some more range of movement is possible to get the board down and
away from the transport mechanism.
The Mode Switch still isn't visible, as it's view is blocked by the small
board at the front, but the majority of the mechanism is visible.

While examining the bottom large board (Video, Video I/O, RF Block, Jog), I
noticed that C219 470uF 10V (Red case, Long Life brand) was wet around the
seal. This cap is a radial lead type, but the leads are bent 90 degrees, so
it will lay on it's side on the board.
After replacing C219, I put a little DeoxIT on the hinged connectors along
the edge of the board, since moving the board after so long could cause bad
connections.

So, without knowing what was the cause of the problem of the floundering
guide post blocks, the proper operation of tape loading and unloading during
Eject has been restored.

After replacing the leaky surface mount caps in the head amp, and an
adjustment/alignment of the tape path, this machine may just operate again.

--
Cheers,
WB
..............