Difficulty fitting new spark plug

[AA77]

Changing the spark plugs on my Fiat 500 Lounge (2010). The old ones were quite rusty. Managed to get new plugs 2, 3 and 4 in (working left to right) but having trouble getting in plug 1. I am getting a lot of resistance after screwing in after about 12 quarter turns. The other plugs were fully in after about 45 quarter turns and only felt resistance for the last few turns. I am reluctant to keep trying to tighten plug 1 with a ratchet, although I assume at this point I could not have cross threaded.
Any suggestions? Could the thread I am screwing into just be rusty?
Thanks.

[AA77]

Many thanks for the replies.
When I removed this plug it was quite tight to undo intially and was also tight as I unscrewed.
I have tried re inserting some of the old plugs and other new ones but I get the same resistance after 10 or 12 quarter turns. These same new plugs screw in fine in the other 3 locations.
As the threads of the plugs look ok, presumably if any cross threading has occurred it is in the hole itself rather than the plug?
The location of the plugs on my Fiat 500 are so tight for space I can not actually put any of the plugs in by hand I have to put an extension socket on the plug and turn the socket extension gently by hand to get the plugs to start threading.
I will try a little WD 40 on the thread but think it unlikely it will make much difference as the plug feels so tight.
Thanks again.

[AA77]

Thanks, that sounds a good idea, didn't know there was such a tool, just found them on Eurocarparts so will go and pick one up later.

[AA77]

Thanks, yes. In fact, I am going to go and see if my local garage will look at this for me. It will be an expensive mistake if I get it wrong!
I've tentatively tried a couple more times to insert the spark plug, but it is definitely getting stuck about half way in. Tried different plugs too, just to eliminate a problem with the plug itself. As mentioned before, when I removed the original plug it felt much tighter coming out than it should so I suspect someone has cross threaded it in the past.

Not sure if I can drive the car a couple of miles to the garage with one plug not fully in? It feels tight and secure but not sure if that is a very bad idea?

[AA77]

Thanks everyone for your help with this, very much appreciated.

Just been to my local garage, they referred me to a local company that repairs threads, unfortunately they can't get to me until end of the month.

Tempted to buy a thread chaser, but a bit put off as it sounds like I could make things worse if that doesn't work. I am fairly competent but the plugs are at the rear of the engine with very little access, particularly the one that is the problem, as it is right next to the dipstick too.

May just have to wait for the thread repair guy to be free.

[AA77]

Thanks Bill, that is my only consolation, it was probably cross-threaded by the last person to service it - that's what I am telling everyone anyway!

[AA77]

Thanks Panamax. I guess it just shows if I ask enough people I will get the whole range of possible solutions. I like your suggestion and in fact I think that may well be what happened the last time the previous owner had the plugs changed, as I am pretry sure the problem plug was not in as far as the others when I removed it.....wish I had paid more attention, I just remember it was particularly tight unscrewing.. Trying to find someone in the Hampshire region who can do the rethread for me that knows what they are doing, will search tomorrow, else may try your suggestion. Thanks again.