Others may be able to give more knowledgeable advise, but I am somewhat
familiar with the gear system on the PA28R, and I believe the system on the
PA32R is similar.

As I see it, you have expressed two problems. The first is that the gear
won't extend reliably with the normal hydraulic activation (accompanied by
the squeal from the pump). The second, potentially more dangerous problem
is alluded to at the end of your post when you state, "however once released
with the emergency extension lever the hydraulic pump would push them to the
locked position if required." The whole idea of the emergency extension
system, which is essentially a valve that releases the hydraulic pressure
holding the gear up and thus allowing it to free-fall into the extended (and
locked!) position, is that it works independently of both the pump and the
electrical system. Your statement seems to suggest that the gear will
free-fall, but may not lock unless given a "boost" from the pump. Bad
situation if you ever loose your pump!

This second problem may in fact be related to the first problem. If you can
figure out why the gear does not reliably free-fall to a down and locked
position, you may also find the reason why the hydraulics won't reliably
extend the gear down. Once place it start looking would be the pressure
switch, which is common to both the main hydraulic circuit and the emergency
bypass circuit.

One more thing: I do not believe it is normal for the pump to squeal, even
momentarily, at the end of the gear cycle, since the pressure switch should
cut it off immediately when pressure spikes upon full extension, but I could
be wrong. Anyway, this would also point to the pressure switch as the
culprit.

I presume your mechanic has checked to make sure the system is purged of air
and is not leaking.

Hope this might be of help. Good luck.

-Elliott Drucker