Hello- i have a 2nd hand Kenwood stereo double cassette KX-79CW

Look on ebay, for starters...worked for me...NK

Have you tried Kenwood site. Some of these sites have free PDF of user manuals.

These dual cassette deck are rarely worth he effort to put repair time into. I checked Hi Fi Engine and they did not have anything. Is it worth a $100 repair bill? if not then look for a good solid single deck.

the standby light should be on if the unit is not 'ON' if you want the 894 to turn on when you power up the 996, then you will have to plug the ac for the 894 into the 'switched' ac outlet on the back of the 996
what specific problems do you have with this system

Yes, the belts need to be check and idlers or whatever drive mechanism that is used in that system. Dual deck units are among the most unreliable units there are and a reason I tell people for the last 30 years not to buy those things. Almost most of the time they are not worth fixing due to their poor performance at the end. These are facts not just opinion.

Outs to Ins.

The flywheel belt would have broken or gone slack and fallen off the motor pulley. You can confirm this by opening the top and looking inside. If you can shake the machine holding it upside down the belt might even fall off.Replacing the belt is a tricky job. Its like putting back a bicycle chain except there is a metal plate behind the flywheel and your hand won't go there.

Connect the RCA Outputs of the Tuner to the RCA inputs for Tuner on the amp.
Connect the output of the Tape Deck to the Tape Input on the amp.
Connect the input of the Tape Deck to the Tape Output on the amp.

Select Tuner on the amp to listen to the tuner.
Select tape Monitor to hear the Tape Deck(s).

I presume you realize none of these things produces speaker amplification. A receiver would do that and facilitate graceful and simultaneous interconnections. But it's not a necessity for selective interconnective between them, just not all at the same time.

I can't find any details on anything you named except the Tuner.

Typically, the tuner would use an RCA pair to go to a receiver AUX, TUNER or other Line Level input for source selection and amplification. Lacking a receiver, run it to the Tape Deck inputs for recording.

Ditto for the CD changer, but you'll probably have to disconnect the tuner.

Needs two new 8" drive belts. They install in 5 mins and cost just a few bucks. [email protected] if you need more help.