Royal Guard Scoring Issue

I'm completely new to this hobby, having picked up a Royal Guard this past spring. Last summer the 10 score reel begin to intermittently act up and not register points. The problem got worse and worse so I took a look at it this weekend. I found that when I manually tripped the M relay for the 10 reel the bell would sound but some times the coil in the reel itself would not fire to advance the reel. I would often have to apply a little more pressure to trip both the bell and the score reel coil.
So I cleaned and adjusted the relay switch contacts so now the relay activates, the coil fires and the reel correctly increments each time the relay is manually tripped.

Thinking that I solved the problem I tried a game only to find that the problem is actually worse! The 10 reel now will increment maybe 1 out of 25 times. When a 10 point switch is closed by a ball the M relay and reel coil are firing but it looks like the plunger is not being pulled in far enough to engage the ratchet to advance the reel. So the plunger pulls in and goes back out and nothing happens. Yet when I manually trip the relay everything works fine, the reel advances every single time all day long! For some reason the reel only has an issue when its relay is tripped by a playfield switch, not when it's manually activated.
I checked the ratchet in the reel, it looks fine, does not bind and moves freely. Any help on this would be appreciated!

Thank you both for your replies! Man you guys are fast!!

So am I correct in thinking that the reason why the reel works when manually tripped and not (most of the time) when tripped by the playfield is because when I manually trip the M relay the duration of the electrical pulse to the reel coil is enough to allow the coil to complete its cycle? But it may not be working from the playfield switches because the End Of Stroke switch is either open when it should be closed, or is closed with dirty contacts, thus keeping the circuit open and preventing the coil cycle from completing 100%?

And is the hold switch on the 10 Point relay physically located at the relay itself? The M relay has 4 switches, and if one of them is the hold switch, I'm thinking that it's working, otherwise I don't think that the reel would work when manually tripped (but I'm not sure on that).

This problem is most apparent when the game is shut off with a 1 - 9 value left on the ten reel. When it's started back up the score motor just goes and goes while the 10 reel coil plunger repeatedly goes back and forth attempting to re-set the reel to 0. If or when the 10 reel does eventually re-set to 0 the game fires right up.

That's OK, I thought the same thing when I first looked at it, and I was using an iPad!

After posting my reply I learned that the M hold switch is one of the 4 switches physically located on the M relay, and my logic may be faulty (in assuming that the hold switch works ok because the reel advances when the relay is manually tripped) because of what I mentioned earlier, it may only be working because when manually tripped the duration of the pulse to the 10 Point Reel is long enough to allow the 10 Point Reel coil to fully cycle.

When a 50 point target is hit the M relay, 10 point bell, 10 point coil and plunger all fire 5 times but the score reel does not usually advance or it will only advance maybe 1 or 2 times, not 5.

When the game is reset (if the 10 point reel is not on 0) the coil and plunger repeatedly cycle while attempting to get the reel to 0. The M relay does not fire while the game resets.

One thing I did notice is that if I very very very gently tap the M relay I can duplicate the problem of the coil and plunger firing but not advancing the reel.

If I give it just a little more pressure when manually activating the relay the reel will advance.

I switched out the spring with the one in the N relay and it now works! Perfectly!

And the weird thing is that the 10 reel now resets immediately when starting a new game, just as it should. I don't know how that happened but I'm not questioning it!

Gentlemen I thank you for your timely and expert advice. You have both helped me fix the machine and gave me some valuable knowledge on how these things work.

Yes the N is working fine.

I did notice that the two rear mounting bolts on the coil relay bracket that mount to the reel frame were only finger tight. I tightened them up
but don't think they would effect the coil/plunger performance because they don't allow for any front to back coil adjustment and the bracket didn't appear
to have any movement at all when they were loose. The two bottom bolts that fasten the bracket to the frame seemed to be enough to secure the backet.

Agreed.

And thank you again. Your help in this is greatly appreciated.