Original pump (now the spare) Jabsco 31620-0092.
The PDF is named Max 3, but the pump is named Max 4!!
Jabsco website: https://www.xylem.com/en-uk/products--services/pumps-packaged-pump-systems/pumps/positive-displacement-pumps2/diaphragm/par-max-4/
The pressure switch kit is part: 37121-0010. Force 4 link: https://www.force4.co.uk/item/Jabsco/Pressure-Switch-40psi-HP/LPD
Source Relay name: TR20-2e5-1 with 15 seconds delay.
Replacement URL: https://www.ebay.co.uk/itm/267204945647
Had to swap the left and right pins for the new relay to work.