Any Panasonic VCR Experts In Here?

I have two Panasonic VCR's, model numbers PV-V4540 and PV-9450.

They are almost idenical on the outside and very simular on the
inside.

The "newer" model - PV-V4540 - seems to have a head going bad from
everything I've read.

The PV-9450 works fine, but doesn't have the features that the PV-
V4540 has.

I would like to install the head unit from the PV-9450 (the older one)
in the PV-V4540 (the newer one).

They look the same, but are they the same? And if I swap the
headunits, will the alignment be the same?

Here are pics of the head units. The one thing that I wondering about
is the "arm" on the center post of the (newer) PV-V4540...what is
that?



PV-V4540  head unit
http://i126.photobucket.com/albums/p96/bigelile/IM002417-1.jpg

PV-9450 head unit
http://i126.photobucket.com/albums/p96/bigelile/IM002411-1.jpg

PV-V4540 face
http://i126.photobucket.com/albums/p96/bigelile/IM002414-1.jpg

PV-9450 face
http://i126.photobucket.com/albums/p96/bigelile/IM002413-1.jpg