lose lock, advice please!

[The Mrs]

Dear All;
We've been having a bit of difficulty opening and locking our front door lately.
What seems to have happened is that the 'euro cylinder' has become loose, such that you can move it a few mm every time you put your key in. To open the door we now have to pull on our key to get the door open, and push on it in order to lock. Is there anyway I could fix it? There are a number of screws, and I thought that perhaps I ought to tighten one, but not sure which and as the door is a bit dodgy I best not do anything without first seeking advice!
I have attached a few photos which might be helpful to identify the problem.
--On a slightly different, yet connected issue, does anyone know if it is possible to change the lock so that it does not automatically lock every time you close the door (or the door is slammed by the wind for example)? I was caught out the other day, with the keys being on the inside and I had to resort to climbing over our garden wall and through the back window to get back in (bruised my knees in the process) As I feel I am getting a little too old for this type of a game, I thought I'd ask!
Many thanks!
The Mrs

 

[rsgaz]

but not sure which

It's the screw that will be dead in line with the hole in this diagram (it's hard to tell which one from your last photo, because the camera is angled downward)...

You should probably take the lock out completely to check whether something has snapped or worn out.

possible to change the lock so that it does not automatically lock

It does that because you have a "split spindle". You need to take it out measure the square dimension and how long it is and fit a standard spindle.

 

[The Mrs]

Thank you so much for all this information, and diagrams to go with it! It will be most helpful!
Thanks again!

 

[Bungled]

You should probably take the lock out completely to check whether something has snapped or worn out.

I agree and, whilst you're at it, it might be useful to use a decent PTFE dry lube both on the lock and in the lock cylinder.

Looking at your lock cylinder, you might also consider replacing it with a more secure one (i.e. a Sold Secure Diamond euro cylinder)

 

[The Mrs]

Thanks again! I will take this advice on board- sounds like a project for the weekend!