Checking the Impeller for Debris
To open the pump shut off power at the breaker and remove the six bolts and pull back the power end.[1]
Don't remove the back cover like he does in the video at https: //youtu .be/Hy1meV5Y4iQ.
Remove the diffuser and check the wear ring and impeller.
Drain Plug
It's 1/4" npt. Most drain plugs are 1/4" npt.[2]
The newer drain plugs are designed with an O-ring.
The O-ring plug is preferable if the pump hole has a flat spot for the O-ring to mate with.
A 1/4" npt plug will work in any case.
1991 and earlier, it's the regular plug (SPX1600V). 1992 and later, it's the O-ring plug (SPX1700FG).
The OD of the plug is about 7/16. That's the name, not really the size. It's like a 2 x 4 is not really 2x4.
Stripped Bolt Hole
One of the bolts holding it to the wet end will just spun and will not loosen.
Hayward makes an insert to repair this type of problem. Part number SP1600TAP.[3] If you heat the bolt, you should be able to pull the old insert out. Pull on the bolt while heating.
Another fix is to gently hammer the offending inserts back in to the housing. Use a 200W soldering iron to heat the inserts for about a minute each, until you smell the pump housing melt a little. Move the soldering iron tip around so that the heat was distributed evenly each time. Leave the pump alone for a few hours for the inserts to cool off and set in well. Then insert the bolts and the inserts may stay in place and seal the housing with no leaks.
