The orange on/off button lights up. however the start/pause button does not.

That sounds like you are on Pause or Delayed Start. Try Pressing and holding the button. You can also try disconnecting from the mains for 5 minutes.

When in doubt, read the manual :>D

START/PAUSE button with indicator light: starts or temporarily interrupts the wash cycles. N.B. To pause the wash cycle in progress, press this button; the corresponding indicator light will flash orange, while the indicator light for the current wash cycle phase will remain lit in a fixed manner. If the DOOR LOCKED indicator light is switched off, the door may be opened. To start the wash cycle from the point at which it was interrupted, press this button again.

and also

! If the START/PAUSE indicator light (orange) flashes rapidly at the same time as the function indicator light, this indicates a problem has occurred (see "Troubleshooting").

https://manualzz.com/doc/50330217/hotpoint-fdl-9640p-uk-instruction-for-use

..

It sounds as though power is only struggling through to the motor intermittently.

Ignoring the possibilities of loose or bad connections or expensive circuit boards the motor could need new brushes.
I have had my machine nearly ten years and it is on its fourth set even though it doesn't get used very often.

I suggest you stop persisting with attempting to make it go. If brushes are the problem you could be making things worse so that it could need a new motor rather than some routine periodical maintenance.

I could be completely wrong - sorry if I am.

Hi Fred, try this and see if it works: To recall an error code,
• Wake the machine by pressing any button

• Wait 5 seconds

• Press and hold the Start and Pause Cancel buttons simultaneously

• All LEDs will go blank and after a few seconds the control will signal the stored code using audible beeps and blinking LEDs. The control will repeatedly signal the code, as long as the Start and Pause Cancel buttons are pressed. A two-second pause between repeats affords you the ability to make accurate counts to identify the correct error codes.
Once you have your code information, you have the option to reach out to the manufacturer to determine what the issue may be, or feel free to reconnect with me and I will attempt to assist you with the best of my ability. Thanks again for your inquiry!

Do the self check this set has when it shuts off Menu and input (input is source) buttons on the set both held for five seconds or longer, then release both and look for the power light to blink a two digit error code like one blink, two blinks and pause then repeat it several times, let me know what error code you find.

WAKE THE WASHER BY PRESSING ANY BUTTON.

WAIT 5 SECONDS.

PRESS AND HOLD THE START AND PAUSE/CANCEL BUTTONS SIMULTANEOUSLY.

ALL LED'S WILL GO BLANK AND AFTER A FEW SECONDS THE CONTROL WILL SIGNAL THE STORED CODE USING AUDIBLE BEEPS AND BLINKING LED'S. THE CONTROL WILL REPEATEDLY SIGNAL THE CODE, AS LONG AS THE START AND PAUSE/CANCEL BUTTONS ARE PRESSED. A TWO-SECOND PAUSE BETWEEN REPEATS AFFORDS YOU THE ABILITY TO MAKE ACCURATE COUNTS TO IDENTIFY THE CORRECT ERROR CODES.

PLEASE NOTE THE FOLLOWING: ON A SMALL NUMBER OF WASHERS WITH SERIAL

NUMBER PREFIX XC4, IF THE PREVIOUS PROCEDURE DOES NOT PREFORM AS

SPECIFIED, FOLLOW THE OPTION BELOW:

* FOLLOW ALL PREVIOUS STEPS BUT INSTEAD OF PRESSING START AND PAUSE/CANCEL BUTTONS, PRESS AND HOLD OPTIONS AND PAUSE/CANCEL BUTTONS."

*THE CONTROL WILL PAUSE FOR 2 SECONDS, THEN REPEAT THE CODE AS LONG AS THE TWO BUTTONS ARE PRESSED AND HELD."

NOTE: A LETTER APPEARING IN THE CODE STANDS FOR A NUMBER HIGHER THAN NINE: A=10 B=11 C=12 D=13 E=14 F=15 "

"EXAMPLE CODE F1: THE FIRST DIGIT WOULD BE 15 AND THE SECOND WOULD BE 1. IF THIS CODE WOULD APPEAR ON A WASHER IN THE GOOD MODEL LINE, THE FIVE INDICATOR LIGHTS WOULD BLINK FIFTEEN TIMES AND THE START INDICATOR LIGHT WOULD

WAKE THE WASHER BY PRESSING ANY BUTTON.

WAIT 5 SECONDS.

PRESS AND HOLD THE START AND PAUSE/CANCEL BUTTONS SIMULTANEOUSLY.

ALL LED'S WILL GO BLANK AND AFTER A FEW SECONDS THE CONTROL WILL SIGNAL THE STORED CODE USING AUDIBLE BEEPS AND BLINKING LED'S. THE CONTROL WILL REPEATEDLY SIGNAL THE CODE, AS LONG AS THE START AND PAUSE/CANCEL BUTTONS ARE PRESSED. A TWO-SECOND PAUSE BETWEEN REPEATS AFFORDS YOU THE ABILITY TO MAKE ACCURATE COUNTS TO IDENTIFY THE CORRECT ERROR CODES.

PLEASE NOTE THE FOLLOWING: ON A SMALL NUMBER OF WASHERS WITH SERIAL

NUMBER PREFIX XC4, IF THE PREVIOUS PROCEDURE DOES NOT PREFORM AS

SPECIFIED, FOLLOW THE OPTION BELOW:

* FOLLOW ALL PREVIOUS STEPS BUT INSTEAD OF PRESSING START AND PAUSE/CANCEL BUTTONS, PRESS AND HOLD OPTIONS AND PAUSE/CANCEL BUTTONS."

*THE CONTROL WILL PAUSE FOR 2 SECONDS, THEN REPEAT THE CODE AS LONG AS THE TWO BUTTONS ARE PRESSED AND HELD."

NOTE: A LETTER APPEARING IN THE CODE STANDS FOR A NUMBER HIGHER THAN NINE: A=10 B=11 C=12 D=13 E=14 F=15 "

"EXAMPLE CODE F1: THE FIRST DIGIT WOULD BE 15 AND THE SECOND WOULD BE 1. IF THIS CODE WOULD APPEAR ON A WASHER IN THE GOOD MODEL LINE, THE FIVE INDICATOR LIGHTS WOULD BLINK FIFTEEN TIMES AND THE START INDICATOR LIGHT WOULD

Some fixya user told me a website reliable-store it is very good.. I used it to repair my shredder it had some spark issue which wasn't easily fixed. you can go there and try free

Drop your drain hose to floor level with bucket under it this will drain with no power applied , pour in as much water as you can to flush it out / clear pump .After all suds clear refit / restart ..Should now fill, wash/ empty and spin...I hope ...

If the status light blinks orange when you press a button, the iPod shuffle buttons are
disabled. Press and hold Play/Pause (’) for about three seconds, until the status light
blinks green.

If the status light blinks orange when you press a button, the iPod shuffle buttons are
disabled. Press and hold Play/Pause (’) for about three seconds, until the status light
blinks green.