The very first thing That you may encounter on a factory 2/4 is a frozen or near frozen mandrel shaft. This is because the center bearing was made of "pot metal", this has a tendency to swell with age and bind the shaft. This step by step guide to replacing this bearing will serve as a good guide to part placement on these mechanisms.
Italics refer to photos
1) First remove the belt, next grasp the mandrel and without bending the mandrel shaft, twist.
If it turns relatively snug (not too tight), then spray WD-40 on the bearing both sides. Loosen, don't remove the set screws on the Thrust collar and the pulley. These are the only things attached to the shaft. Spray the pulley, clutch, and thrust collar with WD-40 to loosen the varnish that has formed. Remove a large head screw that is the adjust for the End Bearing, far left, loosen the set screw on top of the stanchion holding the end bearing. Spray this also. Slide the end bearing as far to the left as it will go (out of the mandrel shaft). If the Mandrel shaft is frozen tight go to #1A,#2and #2A
1A) When the shaft has been seized to the bearing, the only thing to do is remove the Mandrel from the shaft. Sometimes the mandrel is loose enough to twist off the shaft, little bit at a time. All precautions must be taken not to bend or damage the shaft, as this will cause a wobble to the record. Most times you will need to make a puller (piece of wood or soft metal a little larger than the Mandrel base) that will span the shaft behind the mandrel and allow you to lever the mandrel off the shaft, being double aware of the paint and mandrel. A word of caution here, if the job comes to this, it may be best to send the upper works to us for repair. After removing the mandrel from the shaft, place a pair of vise grips on the shaft about mid way, where the mandrel will cover any marks made. have someone hold the bedplate while you twist the shaft back and forth while pulling straight so it will not bend and spraying WD-40.
When you have loosened the shaft so it moves some in the bearing continue on.
2 ) Next grasp the Pulley with your hand, and while twisting the pulley, try to slide the pulley toward the End bearing. After moving the pulley, slide the clutch toward the pulley as much as will go. Grasp the Thrust collar and keep it from turning, with a leather gloved hand (or anything that will not damage the thrust collar or shaft) and pull the mandrel straight out, while twisting it back and forth. If the shaft is not coming lose, spray more WD-40 and keep trying.2A) You must now take the vise grips and while someone holds the bedplate, you twist back and forth as well as pulling straight and away from the bearing. Stop regularly and try to move the Thrust collar away from the bearing. This is slow and tiring but it will remove the shaft with minimal damage, if proper care is taken. After the shaft is removed, replace the mandrel on the shaft, pressing it on if possible.
3) When the shaft is free from the pulley and thrust collar, remove it from the center bearing, being careful not to damage the lead screw and gears. Also be aware that there is an extension rod under the set screw of the pulley and can fall out. When handling, place set screw on the bottom to keep it in place.
Now you must remove the swollen center bearing, cut the back of a hack saw blade, so it will fit into the bearing hole. Now hack saw thru the bearing until you have gone thru to the cast iron. Once thru, the pressure will be released and the bearing may now be removed. Install a Part #2039 (oilite bearing) and reinstall the parts.
4) Place the mandrel shaft just thru the center bearing, place the lead screw into the thrust collar stop engaging the groove with the stop piece. carefully push the mandrel shaft into the thrust collar and lead screw, stopping at the fork pins. Place the pulley and the clutch together so they interlock, and position them onto the end bearing. Line up the lead screw pins and the slots on the clutch and push the shaft into the clutch, and into the pulley (be sure set screw is on the bottom). Most mandrel shafts have a positioning dimple that the thrust collar set screw will set into (its sometimes hard to find). Once set the thrust collar sets the basis for alignment.
5) Next we need to set the detent for the clutch. Position the clutch into the pulley ( twist it to make certain it is latched )with its slot up where you may see the detent grooves on the mandrel shaft. Position the pulley and clutch where the pins are just in the the slots, hold that position and snug up the pulley set screw ( not tight ). using the rim, move the clutch toward the mandrel (4 min pos.) and feel for the latch into the detent groove.
Move the clutch back and forth carefully as you may damage the internal gears if the mandrel is not turning. If you feel the detent on both the 2 min. and the 4 min. positions you need only slide the end bearing into place, replace the large headed screw, allow 1/32 end play on the mandrel shaft and tighten the set screws (not overly). Reinstall the belt and give it a go. Sometimes it may take a few wind ups to get the bearing and shaft worn in ( a little light oil will help).
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