The International Cessna^® 170 Association

Pulled the knob off the inner cable of my carb heat. Would like to replace complete assembly. Any ideas?

You will probably be happy with item "A-730 Glide Free Control" from Aircraft Spruce 877/477-7823. The exact pn will depend upon whether you want a red or a black knob (red is usually reserved for mixture only), and the length. For example, a Black knob, 72" long will be pn 05-13672 ($20.60). (The last two digits in the pn determine the length. Available lengths are 72, 84, 96, and just to change things up, a 10ft length is pn 05-13620)
Univair also handles these types, but they are about $5 more for the identical item.
The knobs may be painted to match your existing interior colors.
(While on this subject, there is also a "ratcheting" type control-cable which is very useful for mixture and cabin heat applications. It will hold whatever position you place it in against vibration, and when used as a mixture cable, the spring-type position lock may be done away with.
I strongly recommend you also simultaneously order a new "bug" nut or bolt-type terminal for the carburetor end. The bolt-type is pn 05-16100 for $0.90. The bug nut is pn 05-16245 for $6.65. Guess which type is my preference.
This is also the time to evaluate how you wish the cable to penetrate the firewall. If you are happy with the original Cessna solution, then fine. But if you prefer a "cable safe" method you might look into eihter a Cable Safe or Cable Safe-II.
All these parts are viewable online at http://www.aircraftspruce.com/

Speaking of mixture cables,I have the rachet-type that George mentioned. I really like it,I think the vernier type would be the ultimate but the rachet or click type is the next best thing.
The mixture control has gradually been getting harder & harder to operate. I finally realized that it had gotten downright stiff and took the cable loose at the carb end,pulled it out,wiped it down with gas & then with heavy-duty spray lube (like motorcycle chain lube). I also shot as much of the lube as possible into the housing from the uphill (panel) end. After reassembly,I couldn't believe how much better the mixture control action is!
When something deteriorates gradually it's surprising how bad you can let it become before you realize something's not right. I lubed the other cables too,while I was at it.

Eric