What solvent will safely soften paper feed rubber rollers?

Had the same problem with my Officejet 100. The rubber rollers that pinch and grab the paper are dried out. i stuck my fingers into where the rollers pinch the paper and pressed paper feed to activate the rollers to spin. Transfered some oil from my fingers and it started working again. Best would be to apply some rubber softener to the rollers.
Conclusion is HP makes low quality printers, made of poor quality materials. All HPs profits come from robbing their customers by ink sales

Your paper is too smooth for the rubber rollers to grab it.
You need to wet the rubber rollers. Ever licked your finger in order to turn a page in a book? Same concept solution here.

Remove the paper tray. Take a look inside the space created where the tray was, and locate the rubber rollers. Lick your fingers, and use them to moisten the rubber rollers.

Reset printer and print again. Or try "un-smooth" the paper where the rollers grab it.

Your paper is too smooth for the rubber rollers to grab it.
You need to wet the rubber rollers. Ever licked your finger in order to turn a page in a book? Same concept solution here.

Remove the paper tray. Take a look inside the space created where the tray was, and locate the rubber rollers. Lick your fingers, and use them to moisten the rubber rollers.

Reset printer and print again. Or try "un-smooth" the paper where the rollers grab it.

There are rubber rejuvinators available, usually from office supply stores, or local computer/copier service outlet.
Typically the rollers should be replaced if they get too dried out, paper feed rollers are usually easy to replace, and available through the product supplier.
Hope this is of some help.

change or clean the feed pickup roller in the tray unit. To clean it take some alcohol and a cotton rag and clean the rubber roller

You may not have to replace the rollers. I had that same problem and all I did was turn the rubbers on the rollers inside out. The problem is that the rubbers have become too smooth to grab the papers.

First check if the feed rollers are 'Slick" with paper dust, if they are ,clean then with 409 on a cloth rag, and scrub till u dont see the white paper dust on the rollers, let the rollers dry, then reset the printer, by turning it off. then turn it back on ,reinstall the paper and begin printing again.

CLICK HERE for the manual

See page 55 for cleaning the media roller.

Check to make sure the paper sensor tab moves freely. You might try air dusting around the paper pick-up rollers to make sure the area is free from any accumulation of dust, dirt, or paper residue.

I just finished fixing my ml-2510 with the identical problem. you can take the pick up rubber and its housing off without removing the shaft. after taking off the front panel and taking out the upper paper tray and the toner you have lots of room to get your hands in there (make sure it's unplugged before you start). two plastic side supports hold the rubber housing in. lift the tab on one and slide it to the side. the housing will now come out . take note of the positioning of all these parts before taking them apart. I sometimes use a digital camera for this purpose. the housing snaps apart and the rubber band slides off. I turned it inside out and put everything back together. works great now (for another year I hope). It's not difficult, it took me about 30 minutes, but be gentle with these plastic parts. I needed a small flat head screw driver and a good lamp. the easiest way is to stand the printer up on its back and reach down inside the hole with the lamp set up over top. good luck.hope this helps.