Lost the nut off the central post (holds on fan), apparently it is a strange thread, no one can match it that i've found

They are stocked in the Home Depot lighting department as part of a lamp making kit or as spares. I have one in my garage as part of a drop lighter I found in a waste skip at Bell Canada. :>D

Any nut of the same size and thread. Take the other nut into a motor factors, a garage, or home depot.

seem to remember that this is a viscous fan ,the big nut holding it has a left handed thread and is 32mm ? if i remember rightly

have you checked that you are threading it correctly? I have found that even one missed step can cause major problems. If it is threaded correctly then you can try oiling the machine per the manual instructions. I have also found that my machine works best when using Maxi-lock thread. Some of the cheaper threads are not able to hold up to the commercial speed of this machine.

the plastic posts are guides /support they just slide into place attached to lens just slide/pull the lens off

The saw I own has a thumbscrew-like shaft protruding from the area where the blade guard rests over arbor of the saw, and you simply turn that thumbscrew to loosen the clamp that holds guard on the end of the motor housing, then lift the guard up and over the blade. (After unplugging, of course.)
I don't remember which way it's threaded, but it should be pretty apparant after you take the guard off, as you can see the threads sticking out about 3/4" beyond the lock nut. This allows for the use of dado sets, etc. on the radial arm saw.
By the way, you might be able to find a manual for your saw, if you can find the model number stamped on the plate, by looking at this site.

I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!

You might be able to find a manual here.
You need to lock the blade in place so it doesn't rotate when you loosen the arbor nut. Many older rockwell saws actually had a detent ground in the shaft behind the blade that allow the use of a second wrench to hold the shaft from spinning while the nut is loosened. It takes a special thin wrench to get in there, and the ones that came with the saws were bent just behind the head of the wrench to get around the blade and out the throat, but if you know anyone with a delta tablesaw they may have one you can borrow, or perhaps you can grind down an old cheapy that fits.
If that's not the case, try the instructions I gave in this link.

I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!

Hello. I see that you are in the UK. Here are two possibilities to solve your problem.
1. Order the part from the manufacturer at http://www.mountainbuggystrollers.com/parts.cp
2. Take your stroller to a local hardware store where they will be able to match the nut with one from their stock. Even if you have to go with a metal replacement, you will still have the use of your stroller. Also consider a product called Thread-Lock or Loc-tite which is an adhesive paste in a tube which you apply to the threads to keep the nut secure.
Regards, Joe PS kindly rate my answer. Thank you.

Where I live there is a bolt shop....really. If you can, find such a shop, and take your other bolt with you and 'match 'em up'.

Another possibility is that Lowe's carries speciality bolts. They're in cabinets/drawers in the hardware section, not hanging on the wall. H/Depot probably has a similar arrangement.

Yet another possibility (and I think it's your best shot) is that, if you can match just the threads, you can buy a piece of all-thread (it's just a piece of steel rod, with the threads running the full length of the rod). Thread your nut onto the all-thread just past where you are going to make your cut, and cut with a hack saw. (You run the nut down on the rod so that, after you make your cut, you unscrew the nut over your fresh cut to straighten out the threads deformed by cutting). Total cost for all-thread and nuts......around $5. Use your existing bolt as a pattern for the new bolt, and leave evough extra to accomidate the nut that you'll add in place of the head of the old bolt. Anyone working in any hardware department anywhere on the planet worth their salt can help you.

Best regards, --W/D--