I thought I'd update on this and let everyone know what the results were.
The shop that did the service on the pump said 'there are some worn parts
and we need to replace them'. Two weeks later they were still unable to get parts
so I took the situation in hand and ordered new plunger/barrels and delivery valves as well as a full set of seals
. Almost $500 USD in parts.
It took a week or so for the parts to be delivered by a friend who brought them down from the states to Puerto Vallarta
. It was a miracle, actually, because all these parts are packed in fuel. Imagine trying to carry on a plane three plastic cylinders, about the size of a shot gun shell, with a piece of metal in it and a 1/2" of diesel fuel in the bottom.
The injection shop got the pump back to me in a couple days after receiving the parts and charged me $200 in labor. I installed the pump in an afternoon (it only took me two tries to get the timing right).
So, after paying for a marina for three weeks and $700 USD for parts and labor I have a re-built fuel injection pump that runs about the same as it did before. At least it doesn't leak fuel, which was the original problem. A _new_ injection pump is about $1000.