Why is older dishwasher not washing well?

 Have a Hotpoint dishwasher from 1988. Still seems to run fine but does
a hit and miss job of cleaning. Leaves a noticeable film on glasses on
the top rack, is hit and miss on plates. Doesn't seem to matter what
detergent I use.

As far as I can tell there's still a strong jet of water getting
sprayed, gets plenty hot but it clearly seems to be less effective.
Any insights as to why this is?

Thanks

 
poor detergent, add TSP and it will clean well again. a teaspoonful
will work fine.

that real tsp generally with a red label.

you might try cascade complete it works good

 
Obstruction internal to the water delivery system for the upper rack?
Water quality?

I have had good success rehabilitating older dishwashers using Finish
powdered detergent in the "pre-wash" soap holder and Lemi-Shine in the
main soap holder.

Over time, especially in machines with "heated wash" or "heated rinse"
or in harder water areas, hard water deposits can build up on machine
surfaces.  Lemi-Shine works to remove old deposits and keep new ones
from forming.

Lemi-Shine is a citric acid product.
As an aside, Lemi-Shine will brighten copper bottom pots & pans, by
eating off copper corrosion products (& possibly some of the copper?)

GIve Lemi-Shine a try   .....  about $4 at the grocery store, also
available online.

cheers
Bob

 
FEDS REQUIRED DISHWASHER DETERGENT MAKERS TO REMOVE TSP, to prevent
excess algea growth in rivers and lakes.

the now reforumlated detergent doesnt clean as well.

TSP just a teaspoonfull works wonders, the inside of my machine was
scunge city. Much cleaner after just one load of TSP added detergent

 
So adding TSP to the dishwasher would contribute to "excess algae
growth in rivers and lakes", would it not?

cheers
Bob