How to get jet covers on my lasco tub white they turned yellow

Fill the tub until the jets are covered by 2-3 inches of hot water. Add 2 Tablespoons of a low-suds liquid dish wash soap and 1/2 cup of white vinegar. Run the tub with the solution to clean the jets. You can also use bleach instead of vinegar.

Ok, if this is a heated tub then it is possible that it works off of 220-240 Volts AC. Either you have a disconnect close to or connected to the tub, or it may be wired directly to the main home panel. One side of the 220 volts circuit breaker may be tripped. (being that what makes up 220 volts is two lines of 120) Your circuit breaker may look like it is not in the tripped position, so shut off the circuit breakers then turn them back on again and see if that may have helped.

Yellowing is a sign of age, but plastic items can be brightened up a bit. Here are some suggestions:
http://www.howtocleanstuff.net/how-to-whiten-yellowed-plastic/

It is always possible to add a heater to any jetted bathtub at any time.
What you need to find out that is if the tub is plumbed to each jet with rigid PVC pipe or flexible PVC pipe.
If it is plumbed in flex pipe then the Tee heater will be easier to install however if it is plumbed in rigid PVC then I would suggest a inline pressure heater that you will install in the water line any place after the discharge of the pump.
Here is a link to a installation instructions so you can see how all heaters are installed.
US Parts Center

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Click on the link below and then under the Product Options use the drop down menu to choose the color of the item you need. You must match up the jets you have in your tub to what is shown online.

http://www.uspartscenter.com/index.asp?PageAction=VIEWCATS&Category=387

Try Guillens.com or usparts.com I have had some good luck finnding jets. Maax is still in business and you might be able to get the jet directly from them, although they are in Canada. Hope this helps.

you need to use a cleaning solution to get the bacteria out of the plumbing lines. suggestions: Jet Cleaner

Sorry, the tub will have to pulled out to find out what is leaking so it can be fixed. There is just no other way UNLESS you can open up the wall on the blind side of the tube. (but its probably and exterior wall...if the house is vinyl sided, it can be done. If brick, you'll have to pull the tub). If you just wanted to convert to a tub only, maybe Bathfitters has an insert solution...

The jets turn yellow from exposure to the sun, not much you can do except replace the jets (costly). What is leaking? if you broke the seal on a jet it will leak and have to be resealed.