It always says remove the cassette and I dont unerstand the problem

If you can't reassemble your cassette player, my beast advice, don't spend good money repairing it. You should consider the option of removing it completely and install an MP3 player. Cassette tecnology is outdated. The quality of cassette recordnings never have been good, the "hissing" is always present, even in some of the best quality recordings (well, just fine for casual listening while driving a car), the ribbons entangle - sometimes I had to remove it in pieces form my old player in my late car etc...
Finally, I don't believe anyone can give you instructions how to reassemble a device without even having idea about make, model and the damage it has.
If you really want to repair ir, you should find a repair service to do it.

This should help. Good luck !

Cassette (Tray 2) paper pickup and feed rollers

To remove the paper pickup and feed rollers

1 Remove the cassette.

2 Locate the two rollers on the bottom of the paper pickup unit (above the cassette). The pickup

roller is the smaller roller, and the feed roller is the larger roller.

3 Pinch the tab on the end of the cassette pickup roller (callout 1), and pull the roller out.

4 Pinch the tab on the end of the cassette feed roller (callout 2), and pull the roller out.

Figure 6-24 Removing the cassette pickup and feed rollers

Note Always replace the cassette pickup roller and the cassette feed rollers at the same time. Also replace
the separation roller (located in the paper cassette) when replacing these rollers

that woul depend on what type of cassette it has but regardless of that either type requires a specialty tool to remove. the most common one is a chan wrench and the other is a custom socket fitting. for the chain wrench wrap it aeound the cassett so that when you apply tension you are spinning in the direction that locks the cassette, it takes a good amount of pressure to pull a cassette so if it doesnt happen easy dont be suprised. the socket tool does the same as the chain but instead fits on the inside of the cassette in the hub bearing. remove your skewer before trying either one of these things and if you dont already have the tool your probably noy qualified for the job at hand. take it from a bike tech w/out these tools you will not get it to come off w/out ruining it with home tools. most shops are pretty chill, if you just bring in the wheel and ask em to pop your cassette it takes 2 secs so they probably wont charge you and if they do their a ****** shop.

To remove any rear freewheel or cassette you will need to purchase a Park Tool. Park Tool is the best brand when it comes to bike repair. Google Park Tool and you can look through their products. You will need a cassette/freewheel remover. There are dozens of different companies that make hubs and cassettes (gear sprocket). Take a look at yours and see what company made it. You can than find out which tool with properly fit your cassette. These tools are made to fit in a wrench making hand removal easy. Some brands will require a chain whip. The only way you will know which too you need is by find the company name on the cassette/hub. Without this tool removal is virtually impossible. If you need help narrowing down which cassette remover you need you can always let me know the company name and I will let you know the proper cassette tool to purchase.

It may be that, if it's not the tray allocation settings causing the problem, some printer maintenance will fix this. I had this problem, after I had only had my MX870 a couple of months. Suddenly, it would not print from the cassette even when printing to standard A4 plain paper. Nor would it print from the cassette even when I changed the printer settings from 'automatic' tray selection to print always from the cassette. After seeing something online, I then ran some of the MX870 maintenance applications, first 'Cleaning', then 'Print Head Alignment', and finally 'Roller Cleaning' for the cassette rollers (for which you have to remove all paper from the cassette). The problem has been solved (at least for the moment).

Most of the time this happens is when the tape in in the save mode. check to see if this is the case before inserting.

1. Open the top cover.
2. Pull the lever towards you to release the daisy wheel lock.
3. Remove the cassette daisy wheel by pulling it out of the machine by the protruding "ear' on the top right.
4. Insert the desired cassette daisy wheel into the slot and press down gently.
5. Slide the lever back to its' original position to lock the cassette daisy wheel in place. Make sure to press the lever firmly.
6. Close the top cover.
7. Press [CODE]+[RESET] to move the carrier to the previous position.
(make sure the daisy wheel cassette is not inserted backwards. The "ear" should always be on the upper right.
improper insertion of the daisy wheel may cause malfunction and incorrect printing.
It is not necessary to remove the cassette ribbon when replacing the daisy wheel.
Please check the shape of your daisy wheel cassette before replacing the daisy wheel. The daisy wheel cassette type "B" cannot be used with this machine.)

there is a paper jam att the back of the printer

The cassette adapters are notorious for getting stuck in the deck. More often than not its the wire that comes out of it that causes it. The cleanest and safest way to remove the cassette adapter is to remove the radio, take off the top and "Help" it eject with your fingers or some narrow tool that may get behind it to push it forward and out. If you dont want to take the deck out of the dash, you can try pushing the eject button while manipulating the adapter wire, but I dont recommend it. Its just better to take the deck out. Good Luck

having the same problem...when I put a new tape in it just ejects it right away!