The only way to force it through the sealing ring was from the inside. I'm using silicone sheathed cable of about 7.5mm diameter. You may have to experiment with different cables to get a good fit. The largest cable that can be forced through the ring is also the smallest that the grip will reliably hold. It contains a 'stretchy rubber sealing ring' (I can't think of a better way to describe it) and a separate cable grip. It has spring loaded wire clamps, which are not as reliable as screw terminals in my experience, and the gland - if you can call it that - is very poor. If they'd made the plastic any thinner, you'd be able to push your finger through it. The electrical inlet is of very poor quality. If you're designing a heating system and you need a graph of flow against pressure, you're very much out of luck. There's no information about the pump at all. The manual - if you can call it that - is minimal. The choices were Grundfos (very expensive), Screwfix (cheap but with rather too many bad reviews for my liking) or this one. It soon became apparent that I couldn't get a like-for-like replacement.
When my Myson CP53 packed up after more than fourteen years' service, I needed a replacement and I didn't have many opportunities to go shopping.
Or should I say, you rarely get what you didn't pay for.
