JCB Petrol Chainsaw Model PCS38

A few months ago I purchased a new JCB-PCS38 chainsaw in anticipation of a few trees that needed attention. I bought the JCB chainsaw because I thought it would be good quality with good backup.
I started it for the first time two weekends ago and it ran perfectly, for about 40 minutes. There was a tendency to stall if the throttle lever was opened too quickly, and then, whilst ticking over nicely, it suddenly died and wouldn't restart.
I've since discovered it will still start and run, but only on full throttle. It will not run at low speed or tickover.
I suspect a fuel/carburettor problem, such as a blocked idle jet.
As it is still under guarantee, I spoke to JCB who agreed there may be foreign matter in the carb. They seemed quite happy that I should have a look myself, which I'm prepared to do. However, when I asked for a workshop manual or exploded parts diagram, I was told there wasn't anything available. It also seems that very few spares are available, just air filters, chains and chainbars really.
I understand the carburettor is diecast aluminium rather than plastic like some I've seen. Also, the jets are crimped in and not removable, so a good blow-out with an airline seems appropriate. There are what appears to be three adjustment screws on the left-hand side, visible through holes in the yellow plastic casing. From memory, one is marked 'H' and another 'T'. I couldn't find out what these screws adjust - does anyone know?
Does anyone have experience of these chainsaws? Are workshop manuals and/or parts diagrams available? Are spares available - I imagine a new primer bulb will be a common requirement?
The chainsaws are made in China and I guess to an extent they are just a JCB colour coding and badging job. Are there other versions of this chainsaw around, sold under some other companies name, with maybe better documentation and spares backup?
Any help/advice appreciated.
--
Mike
-Please remove 'safetycatch' from email address before firing off your
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On Mon, 18 Aug 2008 18:08:04 +0100, "mlv"
I hadn't even heard of this saw. Before you fiddle about can you easily remove the exhaust and squint into the barrel? If so have a look at the piston ring as you turn the engine over and the piston moves past the port.
AJH
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On Mon, 18 Aug 2008 18:08:04 +0100, mlv wrote:

=================================I don't know anything about your chainsaw but this place has an enquiry facility and their service (for a few bits and pieces) was good:
http://www.espares.co.uk/?WT.mc_id=eml006
Cic.
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The H screw is to adjust the mixture at full throttle, the T would either be to adjust the mixture at tickover ( I have normally seen them marked L for low) or if attached to the throttle butterfly is for setting the tickover speed.the other screw will be for whichever one T isn't.
Chris
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On Mon, 18 Aug 2008 18:08:04 +0100, "mlv"

I would check out your oil/fuel mix first, as they are very prone to incorrect mixtures.
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dutchman wrote:

I had this happen on a stihl hedgetrimmer: turned out te clink was blocked. Dismantled and blew backwards down the fuel tube and junk came out. Reassembled and its fine..
overall your engine is running very lean..that's classic for 'stalls on throttle open' and 'wont run at all'
Why it runs full throttle is a bit of a mystery, unless its a carb with two jets and the low speed one is blocked.
Oh..another possible is an air leak somewhere around the throttle area..that has less effect at full throttle. E.g. a carbuettor that was half falling off might show this sort of behaviour. Or a cracked crankcase.
Has it been dropped?
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wrote:

Classic sign of ring stuck in its groove, at full throttle the blowby is less significant.
AJH
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