Lubrication Points ??

Have owned the printer since it was new, without any issues. Recently, after several years of use, it sounds as though it may need some lubrication on one or more of the sliding parts. Printer has recently become very noisy as the bar slides back and forth. I obtained a tube of white Lithium grease and spread a small amount on the bar, (which is readily accessible from the front), without success. The *screeching* noise is still present. I love this printer and do not want to damage it in any way as a result of my negligence, or by putting any lubricant on the *wrong* places.Being retired, and on a fixed income, I wanted to exhaust any possible *fixes* to eliminate the noise, before I take it in to what I call the *hundred-dollar-an-hour-boys* !!! If this a lubrication issue which I can address, could you please instruct me as to the appropriate lubrication points.Thank you , W. Sterling Keller