How do I record on tape from the micro?

Depends on what you try to input on the AUX. If you try to connect an old record player it won't work. The AUX needs an input voltage of at least 0,18 V (180 mV) and can handle voltages up to 10 V. an old record player only gives a few mili volts, so it won't work.
If you have an old Tape deck, that you can use to test the AUX input.
I don't think inside your receiver is anything defect. like the switch, but in rare occasions that could be the problem too.

Recording from tape is very similar to recording from the turntable, but you have to select tape as the source. There will be a button labelled something like PHONO/TAPE/AUX with which you select TAPE and then record as you would for a vinyl disc but you press play on the tape instead of playing a record. Here's something very similar which should help you. Good luck and I hope you get to save your memories.

http://www.teac.com/content/downloads/products/755/lp-r550usb_om_efs_va.pdf

Hello may be you try to say what type of tapes used your unit, if yes it is a micro cassette size see link for some available for your unit. http://www.tvps.com/Departments/Dictation-Accessories/Cassette-Tapes/Micro.aspx

Has the tape been erased by being placed on or near a magnetic field such as a speaker or TV?

Did you plug the mic into the mic input?

I assume you want to record from tape to computer and monitor the recordings later.
Simple three steps.
1) Connect the tape deck line out ( or labeled PLAY ) to any one of the inputs like Aux / Tuner using an 2RCA connector.
2) Connect Rec out from the SUV' to line input of your PC ( blue socket ) sound card.
3) To monitor your PC sound after recording on to Hard Disc , connect a cable between the PC sound out ( green socket ) and the the SUV Tape monitor IN ( sometimes labeled PLAY ) Now comes the tricky part.When you want to record on to your PC put the source switch on the SUV to where you have connected the Tape deck ( Aux / Tuner ). On the SUV keep the Tape Monitor switch to source ( released position ). After having done the recording to monitor and hear the Hard Disk playback turn on the Tape Monitor switch ( dipress it ). The pressing of the Tape switch on the SUV lets you toggle between the source and recording - In your case Tape deck and PC

Record players require a PHONO input on an amp.
Most amps no longer have this, so you will need to source out a pre-amp for the record player, and then you can plug the record player into the pre-amp and then hook the pre-amp into a tape, DVD or AUX input.

Can't you simply take the tape from the 2750 and put it into the other Dictaphone to play it? Or is the other Dictaphone a different size tape (eg; mini or micro)?

You need a set of RCA AV dubbing cables (available at fine electronics stores everywhere), and a couple VCRs. Plug the cables into the "A/V Out" jacks on the back of the VCR that will be playing, and into the "A/V In" jacks on the VCR that will record.

Also on the recording VCR, use a regular coaxial cable to attach it to a television.

Now, set the TV to 3, fire up the VCR's, and set the recording VCR's TV/VCR toggle to VCR. Also on the one that is recording, set the channel to "INPUT" or "AUX" or something like that. (You're telling it to record what it sees coming from the jacks you plugged the cables into.) Then hit Play on the other machine. You should be able to see your tape playing back. If you do, you have followed these directions correctly, and you're ready to make your dub.

HINT: The first few feet of tape are often prone to dropout and generally sucking. Record a minute of black before making your dub. Mark this on the tape or tell them when you turn it in. They will be impressed.

Vdumitre -

No, not usually. If you've recorded a tape at LP and put it another machine that doesn't have LP, it usually won't play properly. Some machines that have only SP/EP will do this, but they are got scarce as more manufacturers dropped the LP speed. Your best bet is to buy an older one from a thrift shop or a garage sale, making sure that it will play LP. Then, copy your older LP tapes to SP or EP (Run the OUT from the LP unit to the IN on the SP/EP unit, and choose "record from line in", "aux", or "rear input").

Thanks,

videoman7

you mean to record?first,you must connect the other unit (if you are using two cassette)by using rca plug or earphone plugs.insert the plugs to audio in or aux(this is the unit that will record).if the other unit doesn't have the output audio,use the earphone out instead.time to record.the recorder must be set to tape/aux,(if you are using a unit with radio setting).then,push the play and record button at the same time.don't forget to put in the blank tape ok.then push play to the unit that you want to be recorded.the square symbol is for stop.the arrows pointing left ,rewind.pointing right, forward.the big arrow pointing right is the play and the button next to it is the record button.