Quick Release Chuck Key

Hoping someone might be able to assist me here?
I've acquired a Parkside PFS 710 A1 sabre saw, Lidl brand of course.
It's almost new and had very, very little use.
There are no instructions in the box and it's not possible to speak with the original owner at all.
I have been looking at the user manual on the internet to try to find out how to insert the blades into the chuck.
They state:
Turn the quick release chuck and hold it in the turned position
Press the selected saw blade upto the stop into the quick release chuck. The saw blade should engage.
Release the quick release chuck. The chuck must then return to its original position. The saw blade is now locked in place.

Trouble is I can't budge the quick release chuck!
Anyone familiar with this budget priced tool and how to deal with the chuck?
Any topical suggestions welcome
Curly

 

No, but I'll squeeze a some on tonight and leave it go to work overnight, good idea thanks DD.
It feels as though the chuck is locked in position, although I'm no Charles Atlas I can usually deal with twisting mechanisms.

 

Well I've got good old fashioned 3 in 1 oil and WD 40, think I'll dust off the 3 in 1 though

 

Been baby sitting Grandson all day and away from home
Doused in 3 in 1 again this morning before we left home at 6am
Just got in after an horrendous drive home, white water rapids some roads between Leicester and Burton, so not in the mood to mess with the saw
I'll douse it again tonight when I've finished recovering with the Appletons and have a look see tomorrow.
Thanks for the input Joe, I'll check that out.

 

Eureka, 48 hours bathing in 3 in 1 oil has done the chuck the world of good, after a careful wiping clean and dry it opened nicely, blades in and out with no trouble at all!
Thanks to all for your interest and suggestions.
Curly

 

There's always more to do Joe!