HELP ! - Its a bubble free zone and I'm confused

[rogerds]

New to the forum so please forgive any (unintentional!) breaches of etiquette...
Have lurked as a guest for a while and learnt from you all so thanks for that
Anyway... New to me, but ageing hot tub, all pumps and heater work fine but..
Air blower pump working and blowing but no bubbles
Sounds as if its straining (like a vacuum cleaner when its blocked) and if i disconnect it from the air tube the revs drop to what i assume is the normal level, similarly, if i undo the lid of the 'scent container' and release the pressure there
So, I guess there must be a blockage in the plumbing ? or maybe check valve stuck?
If i blow into one of the air jets, air comes out of another ( so the innards of the manifold must be clear?)
so.... took the plunge (sorry , sides off and tracing tubes through the foam (but remember i'm new to Hot tubs as well)
Eventually (!) I find the check valve but now i'm confused - please see the schematic and the photo
1 - shouldn't the check valve be on the 'down side' of the protective loop arrangement?
2 - is the check valve the right way round?
3 - looks an untidy arrangement ? a botched previous repair?
4 - would it actually work like this?
If i run the air blower - there is a 'bubbling' and 'gurgling' sound from the check valve area as if that is all full of water
Help! - I don't know what to do now - any advice and suggestions most gratefully received and thanks for getting this far !
cheers - Roger

https://photos.google.com/photo/AF1QipPYdHhuXyG6RcrEe6OnVzBpstwNvlgXegTioMA0
https://photos.google.com/photo/AF1QipPZpgUpkHe0M6FQrziudv-57xifmbte-E_-RfBK

[SerjicalStrike]

What kind of spa do you have?  I assume it is a Sundance.

If your air blower has a plastic housing and not a rubber housing, you should be able to disconnect the power, remove the screw holding the blower in, and pull the whole unit out.  There should be 4 nuts you can undo.  Once those are undone, take out the bolts and pull the housing apart.  There should be a large worm clamp.  That could have possibly fallen off.  Put it back on and tighten it up, put everything back together, and it should work like it is supposed to.

[rogerds]

thanks for coming back to me
I'm not sure of the actual make, the pumps etc seem to be 'generic' and easily replaceable if need be
I'll try what you suggest - i'll be pleased if you're right - but upset at having chiselled out all that foam !
another experience to pin to life's tapestry !
thanks

[rogerds]

update

OK... so took blower motor out - but probably not what you were expecting ? but cleaned the filters and put it back
Still the same - sounding as if blower motor is straining against a blockage
Looking at check valve -  it is full of water with small numbers of bubbles of air going through when blower is running
Out of curiosity, i drilled a (small) hole in the u-bend before & below the checkvalve., a 'lot' of water came out under pressure (Hole has been re-sealed now )
I'm guessing the problem of no air through the system is linked to checkvalve being full of water and because it has been placed in the pipe where the air is flowing upwards?
My current thoughts are to remove the existing checkvalve, fill in the gap, and insert a new one in the downpipe just before the manifold
Does anyone think this is unwise? let me know?

[rogerds]

anyone any thoughts?? - i'm a bit out of my depth here 

[rogerds]

update!...
i get frustrated if i follow a thread in a forum and folks don't post the outcome so...
out came the the saw...
before
oops! no images


and after

sure enough, when i checked the valve - it was firmly stuck shut!
hoping thats all thats wrong so will now replace the valve and cut out the ??unecessary?? down loop and put the valve just above the manifold and see what happens.....