Hi
Qwerty8, and a warm welcome to the forum. It's always nice to welcome another Scott Bonnar model 45 aboard.
Here are some of my observations regarding your machine.
This old girl has had a hard life and I agree with BB's observations....but I realise that it is an heirloom and belonged to your grandfather, and so you would like it to be restored. To get it to a good serviceable condition will take time and some expense...but the reward will be a machine that will give you hours of mowing pleasure and if carefully maintained will last a lifetime.
As grumpy has stated, this machine would have most likely been erected in late 1974 or early 1975, so she is an early Series 2 twin rail machine.
The bent and cracked rail issue has be be addressed and repaired to an
accurate standard....if it is not, you would be just wasting your time and money.
You may care to read the thread
HERE as this addresses that very issue.
If the cylinder reel runs true, you will need to get it sand or bead blasted, re-paint it to your colour of choice...you may choose powder coating which is my personal choice as it is very durable.
You then take it with the soleplate with the bottom blade still attached, to the engineer/machinist for grinding. He will also supply and fit a new bottom blade
if necessary.
You will need a new double cutter sprocket and also a new primary chain and I'd almost bet that the upper engine driven (small) top sprocket will be pointy and knackered as well. It is no use using a new chain on worn sprockets, as it will flog out the chain on no time....Conversely, using an old chain on new sprockets will ruin the new sprocket in no time flat!
As you would have read in other threads, there is, unfortunately no colour formula available for SB machines, but the hammertone can be colour matched by an automotive paint shop, using the cleaned inside of the handle or chain-case cover.
We will address the cutter clutch issues (if any) when we get to that stage.
