Depends on where the leak actually is. If it is from the 1.5" pipe plug it is easier to get a new one made by Hayward from a pool store, than try to get it replaced under warranty (about $5-$6). Pentair makes the same one in black but it may be a little more difficult to find. they are both the same. I used them for many years. They seal with an O ring. Unthread the old and install the new. Use a screwdriver as a lever in the slot in the plug to remove. When tightening use it to make the plug snug, not overly tight, or the O ring will be destroyed. Install it, turn the system on. If it leaks give it about a 1/8 turn and try again.
If you use pliers the plug will probably disintegrate under pressure and the new crack if you try to install with them.
If nothing else, get a simple 1.5" PVC threaded pipe plug at a home store. A few tight wraps of Teflon tape (5 or 6) and a snug fit will do the repair (about $2.00).
If it is from the larger collar, that just unthreads and can be replaced for about $30.00. Still probably worth not having the hassle of a warranty claim and a leaking filter until it is resolved. Just be sure to get a new O ring as well if one does not come with the part.
