Problems with gear slop on 1997 Unisaw

Can you see if the worm shaft is turning while you move the crank? If the connection between the two is secure, then your worm gear is probably too far away from the tilt gear (or really worn). The tooth contact marks in the dust read a lot like a ring and pinion in an auto differential, they look "high", asking for more worm gear depth.

 I agree Bruce, thanks for your response. I just can't find any way to take up the slack. I'll check to make sure, but I'm pretty sure the gears are turning. The confusing thing is the gears seem to be fine when near vertical. All I can figure is the arc must change for some reason as the blade moves so the gears move closer together near 90º.

I'm afraid I might have to take the top off to see if there is any adjustment from the top side. I think I'll watch a few more refurb videos and see if I can catch something I've missed.

The buttons that lock the wheel on the tilt are worn or damaged, because the wheel won't lock. To fix that, the top has to come off and the entire mechanism has to be removed. I used to love to do that type of thing, but old age has crept up on me and it's not fun anymore. 

That does seem like a lot of slop between the worm and gear teeth on the trunnion.  My saw is older and I have a little slop but not nearly to that degree.  As far as I know, there is no way to bring the worm closer to reduce the slop.  Is the shaft moving axially as you rotate it?  That could make a little backlash issue seem much worse.  I have noticed when adjusting the blade angle, the weight of the motor will allow me to quickly and easily move from 90° but going back to 90° is elevating the motor so it requires slightly more effort.  Your saw looks clean and with plenty of dry lube so I wouldn't imagine those conditions to be creating a problem.

I don't know if you have a lock for the positions but when there is a lot of slop in a worn gear, I always keep pressure against it in one direction.... and lock it. if I have to back down, I back past where I need it and then turn back in that direction to   remove the backlash. I do that in my mill all the time.

Thanks for the help guys.

Big, I also realize the weight of the motor affects the effort, so I use the weight of the motor to help keep the blades position. I don’t notice any movement axially.

Jim, my saw does have a lock, but the buttons are worn or damaged because it will no longer lock the position. 

I do the same thing and it’s a real pain in the butt. With so much slop, it’s easy to go past what I was aiming for and have to go back and try again. That’s actually why I decided I have to try to fix this. This might turn out to be something I won’t be able to solve.

I’m certainly about as far away from an expert as I can be, but what you’re describing sounds like worn gears to me. Stable in one position owing to the vector of the mass of the blade and trunion, but unstable when the weight is cantilevered. In time, the unstable weight would cause more wear to the associated sections of the gears. Especially if lots of adjustment was may on that section of the gear. 

Again, I don’t know what I’m talking about, but it makes sense this way to me. 

My Unisaw has the same symptoms, just not near as severe.  I'm thinking of adding some type of spring to counter the weight of the motor now 🤔

When not at 90, can you move/tilt the blade?  I would think with that much slop, it might not be locked in place.  Could be dangerous?  

My blade has always remained stationary, even when trying to push the motor up/down

Wonder if maybe you have a sheared pin that won't quite allow for a full rotation (yet)?

A sheared.pin could be a possibility but I would imagine unlikely given the torque required to shear it.  If it were only in single shear (due to the roll pin being not centered), it would be more likely.

Thanks to all of you for trying to help me out.
No wiggle, the blade is rock solid in any position once I get it where i want it. 
Ryan anything is possible, this saw might have been like this since new, but because I was a beginner, I never noticed.  Maybe I drank the kool-aid, but this is a 5hp Unisaw that has only made about 100 projects since 1997, probably less than a production shop would do in a few months. I can't imagine the gears on a saw of this quality could wear out this quickly. 
The more I read posts by makers I admire on this site, I have been trying to tune all my tools up the best I can to try and match or come close to the quality of their work. Maybe all I can do is to continue to use the weight of the motor to my advantage when adjusting the blade as I do now.
I'd like to trade up to a small saw stop because everything I make now is small and the Unisaw is overkill at this point.