I have a TG1860G, 1998 vintage, about 900 hours.
My P.S. has not worked for a couple years, it worked great for 4 or 5 years, then quit working when I changed the battery.
Dealer told me I must have hooked up battery backwards... idiots. 4 years later when it needed a new battery again, the P.S. began to work again. I told the dealer... they said "how nice for you". Idiots !
A couple years ago it stopped working again, but like you say, not really necessary.
About the deck raising/lowering... I would check under the fender, and make sure the cog attached to the push button, etc are well greased. Also, check the stepped cog wheel that sets the mowers height... It also needs to be well greased.