Neville Chase was kind enough to share his experience with his lathe. You may also want to read my experience with a plain bearing spindle since there are clearly similarities between the two.
"The information below applies to lathes with tapered roller bearings only.
Use this information as a guide only and if you are not confident that you can do it alone ask someone with experience in lathes to assist.
To remove spindle from headstock - Remove chuck and backplate.Remove collar on front of headstock by tapping around circumference toward bed. Remove gear train cover. Remove gear from end of spindle by first loosening the grubscrew then sliding gear off. Raise the cover over the pulleys and belt. Locate the grubscrew in the spindle pulley and loosen this until the pulley spins freely on the spindle (the backgear should be disengaged while doing this). The large gear (bullgear) is an interferance fit on the spindle and is permanently engaged to it by a keyway. The smaller gear is attached to the pully with pins and rotates with it. The retaining collar on the rear of the spindle is secured with a grubscrew. Loosen this and unscrew the collar. This is also used to adjust the bearing endfloat.
The spindle is an interferance fit in the rear bearing. Tap the end of spindle towards the bed of lathe with a soft faced hammer or place a piece of timber over the end to avoid damaging it. The front insert has a slot cut into it to allow the key on the spindle to pass through as it is released from the bullgear. Once the spindle is free of the rear bearing continue sliding toward bed removing pulley (with small gear) and bullgear as you go. The pins that lock the pulley to the small gear may have loosened with use and could fall out during disassembley.
Once the spindle has been removed clean all parts and check bearings and cones for wear. If the bearings are reusable then there is no need to remove cones from headstock. To install new bearings it will be necessary to remove the cones. Bearings and cones must be replaced as a set. The cones are seated on inserts in the headstock. These will require removal as well. Before these are removed take some measurements so they can be reinstalled in the original positions. The inserts and cones may be very difficult to remove and care must be taken to avoid any damage to the headstock casting. Excessive force or not having the headstock correctly supported could result in disaster.
If necessary remove the bearing from spindle. Check for wear on the spindle at the point where the pulley locates. Also check the inside diameter of pulley. Excess wear to these parts may involve replacement of pulley or spindle or both. Spindles may be reconditioned by having them hardchromed and reground to size but this is very expensive. Pulleys can be repaired by having them rebored and bronze bushes installed. Note - The pulley is stepped and this will require a bush installed from each end to allow the grubscrew in pulley to seat on spindle.
Assembley is a reversal of the above procedure with attention to these points -
Press inserts into headstock in original position. Install cones and make sure they are seated on inserts. Press front bearing onto spindle. Lubricate bearings. Install spindle in headstock and replace gear and pulley assemblies. Install rear bearing on spindle so it is seated into rear cone. Screw on collar with face toward bearing. Slowly tighten the collar to remove end float from bearings. Turn spindle as this is done to aid in seating bearings correctly .Tighten the grubscrew in collar to lock it in position. Do not overtighten as this may damage thread on spindle or strip the thread in collar. Lock pulley to spindle and turn by hand to check that the whole assembley rotates freely. Install collar to front of headstock. Install gear on end of spindle. Replace geartrain cover. Locate belt on small step of countershaft pulley and large step of spindle pulley and lower cover. Screw backplate to spindle and rotate using backplate to check for any binding or parts that may be incorrectly installed.
If all is ok raise belt cover and loosen grubscrew in pulley to allow it to rotate freely on the spindle. Close belt cover. Engage back gear and run lathe to test. This is the slowest speed. Increase speeds progressively checking for any faults. When you are satisfied that everything is running smoothly replace chuck and test again."