You probably won't be able to spin it by hand and pump it up. If you have a priming tool, prime the pump with a big healthy drill motor and get the
oil flowing. It should
oil the lifters up enough to see what's going on.
If that doesn't work, you may be able to do a surgical procedure and pull the lifter pair out through the head/intake. If you took the lifter apart, you may be able to see if something has it clogged up, or if there is an issue.