Inserting and turning 1999 LS400 ignition key required several attemps due to binding and upon inspection observed the keyed shank was badly worn.

Continuing to use a worn key can damage ignition, door and trunk lock cylinder mechanisms....which on information are no longer available from Lexus.

It also causes additional torque induced stress on the plastic key fob shell housing...

So...replaced the plastic key shell/keyed shank assembly....

Now key effortlessly inserts and turns into ignition, door and trunk locks as new again...did not replace key fob electronics, except battery.

About $50 from Lexus including keying (prices may vary depending on year)
Face of keyed shank is worn preventing insertion and, or, turning into lock cylinder
Side of keyed shank exhibits wear notching near top on both sides.
New key shell/keyed shank
Used a squirt of "Lock-Ease" graphited lock fluid penetrant/lubricant to help clear any wear related. residual metallic sludge accumulation in the ignition lock barrel....
graphited Lock-Ease...use on ignition, all door and trunk lock cylinders.

Old plastic keyfob shell on left is shiny, greasy looking gloss plastic which shows every bit of skin oil while new housing on right is more refined, featuring engineered matt finish which does not show greasy fingerprints