I purchased the Casio Wk-1800 in 2000. Moved

If the volume wheel on your Casio WK-200 keyboard is spinning all the way around and not stopping at the "min" or "max" positions, it is likely that the potentiometer that controls the volume has become faulty or damaged. A potentiometer, or pot for short, is a type of variable resistor that is commonly used to control the volume on electronic devices.
Here are a few troubleshooting steps you can try:

1. Power off your keyboard and unplug it from the power source.
2. Remove any batteries from the battery compartment.
3. Locate the volume potentiometer inside the keyboard. It should be near the volume wheel and will have three pins or legs.
4. Check the potentiometer for any visible signs of damage, such as cracks or broken pins.
5. Gently wiggle the volume wheel while observing the potentiometer. If it appears to be loose or wobbly, it may need to be replaced.
6. If you have experience with electronics and soldering, you may be able to replace the potentiometer yourself. Otherwise, it is recommended that you take your keyboard to a qualified service technician for repair.

If the issue persists after attempting these troubleshooting steps, it is likely that the potentiometer needs to be replaced. In any case, it is best to seek the assistance of a professional technician to avoid causing further damage to your keyboard.

Question moved from Cars and Trucks to a Casio Keyboard one.
Easy enough if you can find the part.

https://www.google.com/search?q=casio+wk-1250+parts+diagram

casio WK1250 Parts and Accessories - PacParts

https://www.pacparts.com > model > model_id=WK1250
Mfg / Model No, Description, PDF, Year. casio WK1250, Musical Instrument: Electronic Keyboard, 1998. The following parts are available for the model listed ...

Casio WK-1250 Repair Parts and Accessories - Syntaur

https://syntaur.com > keyboard > keyboard=2080
Casio WK-1250. Released in 1998. The WK-1250 is a 73-note consumer keyboard with built-in speakers. Synth. All photos are copyrighted by Syntaur, ...

Casio Keyboard Junkyard: Welcome

https://casiokeyboardjunkyard.com Used accessories, parts and stuff for Casio Keyboards ... CASIO WK-1200, WK-1250, WK-1300, WK-1350 models are basically the same and use the same parts.

Casio Repair Parts - Keyboard Kountry

https://www.keyboardkountry.com > keyboard-parts
Casio Repair Parts ; Yamaha Brand Key Lube (Small). $3.80 ; Casio CTK-560L Ma1M Light Boards. $9.95 ; Replacement Keys for Casio CTK-491 and Others. $10.95.
Missing: 1250 ‎' Must include: 1250 ..

I got my manual online. Google search

From CASIO, duhhh ?

It sounds like the sustain is stuck on as if a sustain pedal is active. You don't mention if you have one, however if you MIGHT have one and you have used a Roland pedal, that brand is reverse sensed and would cause note to remain on.

Unfortunately the adapter jacks are a bit of a weak point on many keyboards but it is quite seldom the jack socket itself that is at fault.
Often the sockets are soldered directly on to the printed circuit board and are prone to either one of the soldered legs breaking, or even the circuit board itself cracking around the jack socket. 
Whilst it is generally possible, with care, to resolder a broken leg on the socket if the actual circuit board has cracked the whole board will have to be replaced.
If the actual jack socket itself is damaged it should be possible to snip through the legs and remove it before soldering a new one on to the stumps of the old legs. this is likely to prove easier than trying to solder directly onto the circuit board, unless this is something that you are experienced at doing.

Apparently you can purchase a full service manual for the Casio WK-1200 here for a modest price but I have not used this source myself so cannot vouch for how good it might be.http://www.tradebit.com/filedetail.php/2084335-repair-manual-casio-wk-1200-electronic-keyboard

This is a link to WK-500 owners manual.....SD Card information is on pages E-59 thru E-64...
http://support.casio.com/pdf/008/WK200_500_e.pdf

Most of these have VELOCITY sensing and that involves two contacts per note. If the velocity sense on those notes is somehow not working, broken wire or trace on the board or short that MIGHT cause your problem.

Have you tried signing on to your computer as the administrator? I looked at the support pages at Casio and saw how confusing they are. Look at page: http://support.casio.com/information.php?rgn=5&cid=008&pid=114 and page: http://support.casio.com/information.php?rgn=5&cid=009&pid=115. Pay attention to the red lettering. The computer might be considered as the midi out device and the keyboard as the midi in device or the other way around, I'm not sure. Pretend its a telephone conversation with one person talking and the other person replying. I don't know if this helps but you can also try tech support at Sweetwater Sound (800)222-4700.

No.

I have a Wk-8000 & a CDP-200R, the later is the same as wk-500 but with 88 weighted hammer keys.

Since wk-500 can play SMF (Midi 0 & 1) format directly from a SD card and there is enough polyphony to play anything, I don't find any real reason to convert SMF to any "Casio Format". Just get a 2GB SD card and put your SMF files in the MUSDAT folder for the SD CARD using your PC/MAC.