Yeah.
Could be getting damp through.
Could also be from condensation.
If you cover with plastic. Any water on the plastic is condensation. Water under is a leak.
I've never tried this but I've seen it said as a test.
Normally a leak will spread. You get water stains and the surface rots...
Is that a corian worktop which Is man made. Looks like granite but that's where the similarity ends.
It's not cold like granite.
It's not as heavy
Don't ever get solvent near it as will go white but it can be sanded and polishing to remove scratches.
You want water running through the lance before you power on.
Even better to have water flowing though lance at the point of switching on. This prevents air lock.
Other problem is the water freezing inside machine if stored in outbuilding. That will kill it
Looks more like condensation.
If you can get to the other side make sure there is insulation at that spot. Often the edges get missed as it takes effort to cut a narrow bit and shove behind joists
It's a shed so will be cold.
Condensation forms with trapped air so you need ventilation and let it dry out.
You need air flow under the flooring and air flow inside.
Vent either side will give you air flow.
Even in winter the air can be dry. Cold but dry.
What about the shed roof rain...
Option one.
Take it out and apart. Buy new seals if required. Clean up. Fit back and silicone.
0000 wire wool..
Option two.
Clean up as is. Glass scrapers and silicone remover.
Silicone back around.
Option three.
Buy a new enclosure.
Only way to prevent that is clean ever week.
I think greese and moisture can build up inside the electrical bits so even with good cleaning practice it could go up in flames.
All this moisture and crud could spark inside and cause a fire if the device is plugged in although not in use.
I've known washing machines and dishwashers, fridges...
You need to look around house for holes.
Pipes going through airing cupboard ceiling to loft. Are they sealed.
Under bath is there holes in walls where pipes go through.
Windows and doors need to be sealed.
Loft hatch sealed air tight.
They vacuum test new houses and you can get a company...
Did you watch video..
Have you a through draft in loft?
Sounds like house moisture is getting in the loft and not venting out.
Seal up all holes to loft around pipes or down lights.
Loft hatch needs making air tight.
Through draft in loft.
There are thing's you can check and fix to help
Another thing to try...
Remove the two lid screws at the back.
Take the top off.
There is very little inside a washing machine and you will see a pressure sensor at the top somewhere with a rubber pipe going down out of sight.
Sometimes that gets blocked at the drum especially if you use...
Sounds like the pump to me. Maybe...
Washing fine then not pumping out water so not spinning.
Bit young to be worn out though so go look...
Check filter is clear.
Shine torch in and check it's clear.
Nothing wrapped around impeller.
Use finger or pencil to turn the impeller. It will move but you...