spend more fixing Manitowoc B150, buy used Ice-o-matic U150, or ...?

[sfrd]

I've been a lurker in this forum for years, and appreciate
all the info that you folks have provided.
I own/operate a restaurant and maintain all the equipment.
My Manitowoc B150 has been my continuing nemesis.
It came with the restaurant when we bought it nine years ago.
It was poorly maintained before that - no filter - furry condensor -
bent fins - missing and loose slats, and lime, on evaporator - pink and black
slime - the whole works. I've been keeping it clean
and replacing parts as necessary, but lately I've been beaten.
It makes ice, but the harvest is slow, and tripping the
#2 safety limit. After trying all the tricks I've learned over
the years, but I can't get it to reliably harvest. I even
called in my HVAC guy. He evacuated and recharged it.
That didn't help. In reading the manual, and various
postings, my guess is that either the hot gas valve is
constricted (but not completely - it does harvest - just
not quickly enough - and its hot on its output), or someone
suggested the refrigerant lines can disconnect from the back
of the evaporator.

So, my problem in the cost of paying my HVAC guy to keep
trying to fix it versus replacing it. It looks like replacing the
HGV would be a $$$ job, and I'm not sure that's the problem.

I can't afford a new unit, but have a line on an Ice-o-matic
U150 for $$$$. I haven't seen it yet, but the owner claims
its just a couple of years old and in good condition. I was
planning to check it out today, and was doing some reading
today on Ice-o-matic, and see a lot of negative opinions.

Another option is just to hang in there buying ice until
I can find another undercounter Manitowoc. At least
I understand how they work, and the opinion of them
here seems better, but I doubt I could get a good used
one for less than $800, if that.

I'd sure appreciate any advice on either my B150
problem, or which way I should go.

Thanks,

Steve