How can we reassemble our Jacuzzi?

SOURCE: Jacuzzi Hot Water Heating Capacity

Depending on how you heat the hot water, whether gas or electric, is a missing detail in your problem, but if it is electric then your problem is the size, being only 40 gal, and needing probably about that to fill the tub, will always lead to your current position.
If the hot water heater is gas, the chances of it keeping up are slightly better, but again things like the temperature of the water leaving the tank, any mixing valves, etc. will effect the water temp at your tub.  Before raising any temps, make sure you follow local code, as not to scald yourself or others.

SOURCE: yellow ring around jacuzzi...

run fresh water around the jacuzzi it sounds like grease lodged around the pipes of the unit to motor , leave running for half a hour and drain again ???

SOURCE: Jacuzzi jets not pumping out water

Check the jet pump, also where the filter is there are two 90s plastic. make sure that they are both in the water, if all those check out then check the switch for the jets. It sounds like the pump is bad and is not pumping the water. Even if the motor works and the internal parts of the motor seal gets wet then it all needs to be replaced and rebuilt. Very easy to do yourself. Like always be careful and unplug the unit.

SOURCE: Jacuzzi Leaking

you need to pull the jet body out and then put some 100% RTV silicone around the jet body and the inside of the wall fitting. Once the silicone is in place re-assemble the jet. that will solve the leak unless there is a broken piece on the jet body or the lip of the wall fitting.

SOURCE: Jacuzzi whirlpool, air on/off button on tub

If it is a air button that pushes in and comes back up, there is a good chance that the switch (which is mounted on the pump/motor) is bad. If the switch is a touch button on a key pad, the problem is in the control box for the pump/motor.