If the effort is increasingly harder it is telling you something is wrong. There are a few options. Since you already snapped a cable which is not usual anymore, then I would try to figure out what is causing it. The common causes I have come across are:
- Worn or bad clutch perch, pivot pin causing the cable to pull at an angle. Check the perch for wear in the pivot holes and replace pivot pin if worn. Light coat of grease when servicing reduces wear.
- Improper cable routing cauisng binding in the cable of routed to close to the engine or exhaust causing internal lining to melt.
- Improper lubrication used or none getting down into cable. Too many people use lubricants with dispersants such as chain lube thinking that they will keep the action smooth. Wrong! When the dispersant evaporates you are left with a thick lube right? The cable has to be pulled through this goo and adds to the effort needed. I recommend using a light oil only like 3-1. I'll go into how to do it later.
- Binding clutch ramp, bad thowout bearing, bent pushrod or adjuster cocked. All off these require a tear down and inspection.
- Frayed cable at either end or the cable binding at the connection to the ramp.
The above is not in any specific order and I might have brain farted and missed a couple.
Lubing cables is an important and all to often improperly done or not done at all. About every other oil change or three and at least every 10k I remove the clutch cable from the clutch perch and the throttle and idle cables and drip some 3-1 oil in them. I work the cable back and forth to help the oil flow. Secure the cables as upright as possible and do some other tasks and repeat several times. The throttle cables take far less obviously so don't over due it. The clutch cable is partially lubricated by the tranny juice but only as low as where the height is equal to the level of the fluid in the side cover so the whole upper gets dry. The light 3-1 helps a lot here.
If lubing the cable and you know it is in good shape then I would definitely consider a WB EZ clutch. It increases the levrage and does not alter the release point that much. The SE clutch spring set up is pretty notorious for causing a bit of gorilla arm.
Hope this helps.