I would think that if you watch for play in the spindle up and down or in and out you should be able to monitor for wear. if you Check for play remember that as the machine warms up it will get tighter. I have a tendency to over think some of the things you are concerned about but always try to come at it with input from others and make a judgement call from there. Your lathe is a bit of an oddball here in the US and I have not ran across one like it for sale here. It sure looks to be like the Smithy you linked the manual to though. I found that Shoptask in there manuals depending on the year did pack the bearings with grease or not grease them at all. I know on my machine if the oil is too full it will leak out both ends of the spindle. Mine has felt packing around the spindle and not a rubber seal like the newest machines had. I have had my machine about 5 years and have adjusted the spindle bearings once. Get it cleaned up and lubed make some chips and see how it goes! Keep us posted on your machine and by all means ask questions about anything. 