I think he is looking in the wrong place.
The commonest cause for low oil pressure, which in turn causes the tensioner to not pump up, is the gasket between the sump spacer and the block blowing out around the main front delivery gallery.
The cure is to drop the sump and then the spacer and replace the gasket. Don't use the factory gasket though as it is the cause of the problem. They are thin and frangible and can't compress properly. Instead of that use one of the thick aftermarket gaskets available like this one.[You must be registered and logged in to see this link.]
Although listed as the sump gasket for 1100's it is also the spacer gasket. You will almost certainly also need a sump gasket for between the sump and spacer. That would be this one.[You must be registered and logged in to see this link.]
If it has run like this for any length of time it is probably worth dropping the rod caps and checking the big ends for damage but if he's willing to risk it he can just do the gasket.