Bicycle Tutor

Hello,
Please forgive my lack of technical language - I'm a newbie to fixing bikes and don't know the names for parts!
I have an old Raleigh Equipe which I've been using for the past few years and just recently the rear (i think it's called a derailleur) little cog which the chain runs over managed to get caught in the wheel spokes and has bent.
I would like to replace it - (the actual bent piece can't be hammered back into place!). I went into a bike shop with the bent piece and was told that I'd need to get a new s bend.
Now, my question is: will a modern day "s bend" fit on an old 1980s bicycle? On the part to be replaced there is some writing which says 24 28 DENTS TEETH (just in case that helps!) The make of the part is Sachs Heuret, and the bicycle has 12 gears (i.e. 6 cogs on the back and 2 on the front).
I really hope someone can help, as I'm looking foreward to getting this on the road again!

You should be able to use just about any rear derailleur. I think you probably want to get a lower priced one. The high end ones are made for very narrow chains and you might have an issue with it not running smooth.
If you wanted to replace just the bent part from the Sachs derailleur, that will be much harder to find. But you can probably get a whole derailleur that's similar. Try searching "Sachs rear derailleur" on eBay. Looks like there's a couple around $25. Nice to keep the bike looking "period".
Only thing to be careful of is if your current derailleur threads directly into the frame or if it has a hook that gets clamped under the rear axle nut. You'll normally need to match that.
When you get the new part, be sure to review the tutorial on adjusting. Yours went into the spokes because of a very simple mis-adjustment. Take a look at the cable and housing too. If it is frayed and/or cracked, I'd go ahead and get a new one while you're at it.