Keys not turning in van lock and latch issue

[Keitai]

Keep putting wd40 into the lock but it's hard to turn key. I also noticed the lock on the back door if van keeps putting this metal component I'm the way when it engages. Is the easiest solution to get a remote key ? Regarding lock mechanism? I can reset it by using two small screwdrivers pushing this thing down allows jaws to open and engage but getting tedious

 

[JohnD]

When the door is open, is it difficult to turn the key?

Does your spare key do the same, or just the worn-out one?

Where are you putting the WD40?

 

[Burnerman]

I'm finding this a little difficult to understand (did you write it in a hurry?)
However, I'd consider a three piece lock set and a new rear door latch - which should sort all of this.
By the way, WD isn't really the best for locks - go for a graphite spray. That goes for all locks really!
John

 

[Keitai]

When the door is open, is it difficult to turn the key?

Does your spare key do the same, or just the worn-out one?

Where are you putting the WD40?

Yes, when door is open it's difficult to turn the key.

Only got one key

Stick plastic straw deep into key hole and spray

 

[JohnD]

Is this same key equally stiff in all locks?

WD40 in the keyhole will only help if the cylinder has the fault or is clogged with dirt

Unless it happens to drip onto other moving parts.

A cylinder benefits from being clean, but not from being oiled.

Old keys can wear and lose their accuracy.

A spare key is remarkably useful.