Or, use plastic wrenches.
@SAndreasen , I may be wrong, but it seems that this pump project has been posted by you on two or three threads now. If so, we would need a complete, condensed history of what has been done to offer any help.
To answer your question, ANY component has the potential to have a problem (new or re-manufactured), but it is usually not the case. I personally don't know of anyone who has received a bad pump, but people on forms like this one have reported getting a bad pump.
- John