How to adjust chain on challenge xtreme 1800w chainsaw

SOURCE: chainsaw 34cc 350mm bar polun, tha adjusting

Did the cover crack? The adjusting screw is just a common metric screw; the nut has a special tang that engages one of the 2 large holes at the drive end of the bar. When reinstalling the bar and chain, the adjustment screw must be backed off a few turns so the the tang will readily drop into it's hole in the bar. Install the cover (new if old one cracked) and turn the nut(s) down finger tight. Turn the adjuster CW to tighten the chain so that the chain doesn't droop from the bar, but turns freely by hand. Tighten the cover nut(s) and recheck the chain again.

SOURCE: i need the part number for the chain adjuster for

You were a little short with the model number, I think this is what you are after. The IPL for a SCS 38-35 H follows:
http://weborder.husqvarna.com/order_static/doc/MIPL/MIPL2005/MIPL2005_VP0502007.pdf
Page 6;
item 39 is the screw
item 37 is the bar adjustmeny nut
item 38 is I think an e-ring

If I missed on the model please expand some and reply below. I will get back to you. Good Luck. HTH
Lou

SOURCE: unable to locate adjustment control for chain

Not all 345 machines had an adjustable oiler, it is retro fittable if it does not, however if it hs an adjuster, the screw is located on the bottom of the saw between the cranckcase and the fuel tank, just below the sprocket, there will be an oil symbol and a - and + sign there, the pump is three position, for 13/15/18" bars.