Maybe there is something going on there.  Me, I would have just sprayed it with brake parts cleaner, and never looked at it again. I'm not too old to learn.

The splines on the shaft and the pulley should be very square ,with sharp edges. wear from the pulley moving back and forth will make them more V shaped. if you feel ANY play ,I would suggest finding a product called Bearing Mount( Used to hold bearings in place when rebuilding the bottom end of auto motors) to put on the splines before  reassembly and a new washer to place under the nut( the edges on your washer look rounded-show movement- they should be sharp or they will allow the nut to move again). You might also buy a new shaft seal ($10) and the O-ring seal that goes inside the collar the seal rides on. when you finish ,it might be a good idea to paint a thin white strip across the pulley and nut ,so that you can see if ever loosens again .(line will shift).do it right,sleep at night, and never do it again(opinion) .Your wooden cheater won't cut it ,get a lengthof pipe at the hardware store about 6feet long. you can stop movement of the rear wheel by running along bar or pipe through thr rear pulley and across both sides of the swing arm, you can also just tighten the nut on rear brake cable and give your girl 's leg a rest, this will also allow you to not place the bike's wheel against a wall ,giving you room to use a cheater in a downward stroke using your body weight to achieve max torque on the nut.(use a breaker bar , a ratchet won't handle the torque)

Also I'll need to jack the bike up to loosen the rear wheel to get the pulley back on. I have a scissor jack and I was wondering the best spot to jack the bike. How about that strange plate under the bike? Or would the bottom of the swing arm be OK, it has a flat surface.

@verslagen1

OK will do. Do you reckon this is going to need a new seal or would the leak just have been because the bolt was not tight.

I'm finding it difficult to tell if there's any forward back play on the splines, if I do the nut up hand tight, then there's it feels like there may be very slight play, but I'm not sure as to what to do about this as I've seen RTV mentioned but then I've seen not to use that. Or maybe that was if the play was excessive.

So if there is very slight play because you can see from the photos that that the splines seem pretty good, should I use some RTV or not?

Also regarding the o ring part number 37 in my previous post, how do you get to that, because it seems that the spacer 36 does not just come out easily.

thx

correction Loctite item # 39150

To bend the washer....I find it easiest to use the big Channel Lock pliers. The photo you took of your spacer shows it was not bent nearly far enough...it should be flat against side of the nut.

The metal spacer behind the pulley (on the shaft) just pulls out....it is not attached with anything but may be snug.

When the sleeve is out - the oil seal should be easy to pry out. (Once you have removed the screws that hold in the seal retainer).

Don't call him surely!