My Boss ME-70 Pedal doesn't fade out smoothly

BOSS ME70 Factory Reset.
Just do this:

Is distortion changes like we turn the OD/DS selector (changes to Boost-Natural-OD1-Blues etc)?
If so, the OD/DS potentiometer need to replace.

If the changes are like increasing/decreasing GAIN/BASS/MID/TREBLE/LEVEL and also TYPE of pre-amp, then one of PREAMP potentiometer is bad.

It could be that the electronics of the pedal are dirty, or that dirt has collected under it causing it to not depress all the way. Try taking it apart and cleaning it with a Q-tip and rubbing alcohol. Be very careful of any wires or delicate articles.

press pedals 3 & 4 at the same time to swtich to Manual Mode. Hold down EDIT/EXIT and press the MOD pedal. Press WRITE twice.

Good luck!

spray the controll with cleaner. if it dosen't work replace the controll

Sounds like a loose wire to me (because the problem isn't consistent) the most likely suspect is the jack plug. Unscrew the body of the plug and check that the two wires are firmly soldered to the terminals inside.

If they're OK you can pop the cover off the footswitch and check that end. As far as I recall that end of the cable goes straight to a PCB (printed circuit board) so be very careful if you need to solder anything. If the solder around the wire connection is cracked, that's a dry joint and can be fixed with a small blob of solder carefully applied.

If all the cable connections are fine there's a problem with the PCB or the micro-switch mounted on it.

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.

If on battery, battery is depleted. If on adapter, connection is probably bad. Often power jack is broken or has bad soldering.

Personally I recommend the following set up:

Distortion>Effects>Compression/Noisegates/Sustain

This will ensure that the signal won't have any odd hiccups due to an odd pedal setup. But if you play around with different orders, you can end up with some very interested sounds.

There are two types of damper pedal switches, on that is closed until you press it, and one that closes when your press it. It sounds like your Casio is expecting one type and your Roland pedal is the other type. A quick way to test this is to plug a guitar cable into the Casio pedal input and see if the keyboard sustains. If it does, then your Casio requires an "normally closed" switch.

Some pedals have a small switch near the cord or even on the bottom of the pedal that will reverse the switching operation (BOSS pedals, a division of Roland, have this feature). If you can find that, then change the switch position and you should be OK.

If not, and you feel like digging into your pedal, you could take the bottom off of the pedal and check out the switch itself. Many pedals use a switch that can be used either way. The clue will be on the switch itself. If there is an extra tab on the switch that is unused, then switch the wire that is furthest away from that tab to that tab. This will probably involve soldering, but it is nearly impossible to damage anything.
If moving the wire that is furthest away does not do anything, then try putting that wire back and switching the other one.

If your pedal does NOT have an extra tab, you're SOL, unless you want to buy a replacement switch (unsure of make). If this is the case, you are probably better off getting a different damper pedal - preferably one that is marketed as "universal"