Thanks for all the clarification. You are in a good place with this saw. I have several Grizzly tools and all are really solid for their price point. Your machine has given you a couple of decades of service so you have certainly gotten your money’s worth from it. It will be really tough to get a solid recommendation as to whether to keep or replace.
If you feel the base machine is solid you could certainly throw a few hundred bucks in after market stuff at it. Your description of the guide post and the guides in general could make using the tool a daily annoyance. I am afraid that it is going to be up to you in the end. ;-)
"A hen is only an egg's way of making another egg".
– Samuel Butler