Can I reasonably keep this laptop going?

So the first thing I see is that you're running only 2 GB RAM. That's the bar minimum for Yosemite. It will boot but will run like a total pig

Go to OWC for RAM expansion:

https://www.macsales.com/

If it's a Unibody you can take it to 8 GB.

"the skin on the bottom of the case is a little warped"

There is currently a recall on this problem:

https://www.apple.com/support/macbook-bottomcase/

"the battery does get hot at times"

If that's the original battery it might be approaching end of life. What's the battery info say. A hot battery can be an indication of a bad failure that would be very unpleasant and dangerous!

I'd also consider an SSD upgrade. I put a 256 GB SSD in a client's Unibody running Mavericks w/ only 4 GB RAM. I installed Mavericks on it. It was for her daughter in high school and she never used it because it was running so slow. Now she's worried that her daughter spends too much time on it since it's "faster than when it was new"!

Also re:

Yosemite nightmare

I would only consider parts from OWC, 9 years of dealing w/ them, never a problem and incredibly accommodating, knowledgeable and friendly.

Here's a recent post about what we're talking about:

Macbook sound won't turn on

Some of the upgrade does not require specialized labor, just an ability

to carefully read and then follow instructions. A few pages of repair guide

mixed with a few parts of water (or alcohol+water) and then you may be

able to save a few dollars in labor. Shops can get about $100. per hour.

Just don't mix the MacBook or electricity with water. (LOL)

A few may install parts you bought elsewhere; independent AASP shops

that know what they are doing. But they likely would prefer you to buy

the parts from their inventory, if you take it to a shop in your vicinity for this.

•MacBook Repair Guides - iFixit.com:

https://www.ifixit.com/Device/MacBook

Among the listed MacBook repair guides on this page is one that closely

matches your computer specs and also component configuration. To be

certain the parts and repair guide match your computer, be sure to best

identify the computer build model + numbers correctly. Everymac.com

may be of help since they list nearly every Mac produced and show the

upgrade potential, while from Mactracker.ca you can download their free

database application to help identify product and recent upgrade specs.

•How to identify MacBook models - Apple Support

If your computer is identified by you correctly, it appears to be a Late 2009

MacBook 13-inch model, and if so, these specs should apply:

Introduced October 2009

Discontinued May 2010

Model Identifier MacBook6,1

Model Number A1342

EMC 2350

Order Number MC207LL/A

Maximum Memory 8.0 GB (Actual) 4.0 GB (Apple)

Memory Slots 2 - 204-pin PC3-8500 (1066MHz) DDR3 SO-DIMM

•MacBook: How to remove or install memory - Apple Support

Certain models of MacBook are less trouble than others to open up and

replace parts; you may need to consider an externally enclosed hard drive

or an enclosure to use with a SSD, then read up on how to clone current

system from the installed original HDD, to that SSD in an enclosure; then

later on, after further testing, install the SSD into the MacBook. Or check

the OWC macsales pages for a 7200-RPM internal HDD upgrade to help

MacBook go faster than the 5400-RPM (or slower) stock one it came with.

The RAM and battery should be easy to replace, once you get the exact

correct spec parts for the model build series you have.

Good luck & happy computing! 🙂

edited 2x

"very encouraging about the sound issues. Is it time to just start falling apart? Are these little laptops just too old to try to keep going?"

Arrggg,, That's not what I wanted you to see. This was why I referenced that thread:
"Maybe around 2009/10? Anyway, I got a SSD for it, and now it's working really fast."

I think the sound issue has to do with Yosemite.

More RAM, new battery, SSD upgrade? Are we talking a couple hundred or more?

Like $150 plus the battery ( ~$99) It would be easy for you to do the work yourself.

Complete instructions on the OWC site:

https://www.macsales.com/

Call them and ask.

If you send it or take it in for the recall they could do it then. Ask them.