I agree, I had the same problem. The only resonable solution is to rebuild
or replace. I purchased a rebuilt injector pump
from S&W Diesle in Wilmington, CA for just under $600 with a core
turn in. The improvement on my 4-107 was amazing.
The hard part for me was the reinstall. The shaft is splined and keyed, there is only one way for it to fit in. I had to use a mirror and flash light to get things lined up. 2 hours of minor adjustments before it just slid in. Let's just say I remebered my first high school
girl friend when that happened. Make sure the timing marks are lined up and you will be good to go.
For the time and money
, rebuilding yourself is not worth it.