What kinds of dish warmers are there to keep food hot while on display

No one appears to sell replacements. I would suggest you try Walmart or even a catering equipment supplier. They look like a standard size chafing dish.

https://www.google.com/search?q=Gourmet+by+Sansiohome+3+dish+warmer

It appears the same buffet warmer is sold under a number of names.

https://www.grays.com/retail/HMMBFS225/homewares-and-gifts/mistral-select-stainless-steel-buffet-food-warmer?tab=Description

images

https://www.google.com/search?q=chafing+dishes%2C+glass+lid&tbm=isch&ved=2ahUKEwj71_vQ8pP1AhWKrnIEHeisBdEQ2-cCegQIABAA&oq=chafing+dishes%2C+glass+lid&gs_lcp=CgNpbWcQAzIGCAAQCBAeOgcIIxDvAxAnOggIABCxAxCDAToICAAQgAQQsQM6BQgAEIAEOgQIABBDOgcIABCxAxBDOgQIABAYOgQIABAeUOsWWIlpYJ1raABwAHgAgAFriAHdEpIBBDIyLjSYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ&sclient=img&ei=iwnSYbvmBordytMP6NmWiA0&rlz=1C1QJDB_enCA643CA644

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Electric ones use a conductive heating element in the base that heats the container of food that is set on it. Other types of food warming trays (commercial) use hot water to keep food trays warm. Finally there are warming trays like chafing dishes that use an open flame with a fuel canister like sterno to directly heat the food tray.

You can find replacement Salton power cords on eBay.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=salton+power+cord&_sacat=0

Domestic food warmers usually reach a high enough temperature to heat food but not high enough to kill bacteria, therefore creating an idea breeding ground for it.
For this reason it is best to have small quantities of food being served on food warmers at once. The best is to serve it quickly and remove it from the tray as fast as possible. After two hours that the food sits in the warmer it has to be thrown out.
Another danger could be the heated tray and hot water, in case there are childray round, that could get burnt.

Usually food warmers consist in trays of food sitting in a bath of boiling hot water. The hot water heats up the tray, keeping the food warm.
Most domestic food warmers are electrically powered.

You don't have to have it, but it adds something to the hosting environment. It helps keep food warm longer on the plate, and it's especially helpful for things like pasta that tend to get cold quickly.

: If you are using achafing dish (the metal containers buffet food is served in) the best way tokeep it warm is by using Sterno. Sternois a safe, flammable gel that burns at a very low temperature and will stay lit(and keep your food warm) for atleast two hours. It is important to remember to leave atleast2 inches between the top of the Sterno frame and your chafing dish. This will prevent the dish from gettingburned and your food from getting too hot.

The Owner's Guide for the Rival 18qt Roaster Oven with Buffet Server is available here:

http://www.rivalproducts.com/manuals/MANUALS/RO180BR-C_43_18972586.PDF

See Page 6 for full instructions on use as a buffet server.

You would normally fill the removable roasting pan with 5 to 6 quarts of water ot 1/2 - 3.4 full. Place in the buffet server frame and the empty serving dishes and then preheat at 350 degrees until hot.

Place hot, cooked food in the serving dishes and reduce heat to 250 degree to keep food warm. Adjust the temperature and add more hot water as necessary.

Well, this is kind of a big job. you need to disassemble all around the pump and clean screens. Also, clean discharge ports on the spray arms.
Really, dishwahsers do a poor job of removing food, and so plates should be pre rinsed.