Leak from backwash with new gasket?

[Mtym]

Hello everyone, first post to TFP.

Moved in to a new house 2 weeks ago, and we noticed a leak coming from the backwash hose on our Purex Triton tagelus ta100d sand filter. We opened up the filter, and noticed the spider gasket was ruined. We ordered a new one and installed it, and the channels where it sits were in good shape.
However, there is still a small leak from the backwash.

Things I noticed (not sure if they're relevant)
After I turn the pump off, there seems to be suction from the backwash port for a minute. All the water also drains out from my pump if I change the multiport position.
Also, my heater won't turn on (shows a lo error), which I think is from the reduced water pressure(filter psi gauge doesn't show anything)

 

[linen]

Welcome to tfp, Mtym

If the new spider gasket is still in place (I would check it again), and the handle is seating correctly, I would guess the vavle spring is weak and might need to be replaced.

 

[Mtym]

Okay, I will look at it. Is this probably the reason why my heater won't turn on?

 

[silversteed]

Also, check the areas where the gasket meshes up to. I've seen these get damaged and and no seal, I assume from not pushing the handle down all the way when turning.

 

[duraleigh]

Okay, I will look at it. Is this probably the reason why my heater won't turn on?

No...unrelated.

Also probably unrelated to the heater, but if your psi is zero with the pump running (and you have flow) you need a new pressure guage.

Can't help with the heater.