Schaublin 135 belt change

My Schaublin 135 needs new belts, they've stretched and worn and an oil leak on the countershaft hasn't helped. My machine is fitted with a lever type collet closer which doesn't feature in the manual. Followed the instructions right up to the point of exposing the main spindle pulley, but the body of the collet closer is in the way (See photo attached). I can't see any obvious way to remove this part. It has a split collet clamp affair around it, but it has no split's in itself. There are 4 slots machined around it under the split ring, but with a drift it hasn't moved either way. I have a proper C spanner of the correct size but it's at work in my tool box. On the diagram of the ordinary machine I think I can see what it's located on, but unfortunately it gives no indication of whether it's threaded or not.

Anyone previously stripped a Schaublin 135 to change the belts?

Got it, plain diameter and a thread. Really don't see the purpose of the split ring though, can't see what it actually achieves.

Anyway, collet closer removed, can crack on now....typically the manual little reflects the actual job! The manual just say's to remove the plate with four capheads in, then split the pulley, then remove the belt.....I've already discovered that to remove the plate, I fist have to remove the plate bolted to it, and then I have to remove locking nut and the distance piece on the shaft before the plate can actually physically be removed! Having removed the 3 bolts that hold the two halves of the pulley together, it now looks like I need to remove the tail bearing and the locking nut and tab washer before the pulley will split!

Hi sorry to bother you I have a Schaublin 135 later model with a square headstock. Manufactured around 1973
I have been having trouble with oil leaks one of which appears to be coming from the hole where the belt attaches to the main spindle. I see you have changed your belt so wondered if you had experienced any leaks. Also do you know where you can purchase a new main drive belt for 135.
I don’t seam to be able to find the belt size anywhere?
It quite a bad leak, if I leave it over night I lose about ½ litre of oil.
I have sealed up the leaks on the all the oil unions which had been over tightened and now it has moved the leak . I noticed the belt is now saturated with oil from the leak. I have been Desperate to use the lathe and thought I had fixed the leak. It’s an up Hill battle. Electrical problems, switching problems, blocked oil ways, lose drive pully, house electrics tripping you name it I have had to deal with it. Any help much appreciated.
Best regards
kev