JUST WONDERIN IF ANYONE ANYWHERE HAS A BETTER WAY OF KEEPING THE LAST BEND RUBBER EASILY MOVABLE, IM HERE IN WESTERN AUSTRALIA AND WE JUST REPLACE IT EVERY SO OFTEN WHEN IT GETS STIFF AND PACK IT WITH GREASE BEFORE TIGHTENING IT, A BLOKE WE WORK WITH SAID SOMETHING ABOUT A METHOD OF USING A POLYURATHANE RUBBER MACHINED ON A LAITHE ... I DUNNO, ANYONE?

Your problem most likely lies in pipeline length - either too long or too short (puts the line under tension or compression when extended) which may be causing a twist of the boom arm - check measurements! This problem may go as far as the arm(s) before the tip. I have actually even seen a 3.0M pipe develop a bend in it from the repeated stress.

If there is a problem this would also contribute to premature DU Bush wear at the arm pivot points.

Some manufacturers like Putzmeister actually sometimes implement triple lip rubbers to take some flex/slack when boom is extended on some of their booms.

Troubleshoot by fully extending the boom when empty. Undo last 3 clamps on the line. Then clamp up two last elbows. Spin elbows until it feels with ease - thats the point you want. While elbows clamped, Line up 2nd last elbow with last straight pipe. Do the flanges meet flush?

get the wax ring used on toilets heat it up and pack the gasket with it extends the life of a gasket about 10 times the normal .

The best solution I found was to never touch the deck with the hose. When your out of mud, let it hang but dont put it straight down. Went from changing every 3 weeks to about 8 weeks, but still had to regrease anytime I used a reducer.

 The tip elbows (90's) tear up swivel gaskets faster than other pivot points in the system because the weight of the tip hose, reducers etc. hanging from it. This causes a misalignment in the elbows (90's) creating a small gap or space between the two. This gets worse over time as the tip clamp and elbow ends start to wear.

 A shim or spacer ring cut to fit between the tip elbows fills the gap so it wont leak and rotates much easier. I've made these spacers out of five inch plastic water main. (the green stuff) It works well since the I.D. measurment & wall thickness are nearly the same. ABS or PVC is too brittle & cracks too easily. I think a teflon or poly type of material would work best but it's not as easy to come by.

 I've had tip gaskets last over SIX months of regular daily service! I also use an excessive amount of grease on the spacer, the gasket and in the tip clamp when it's reassembled. Half a tube of grease at least! It's worth the time & effort to change it twice a year or so instead of 10 or 12...

THANKS GUYS FOR ALL YOUR ADVICE, ILL BE SURE TO TRY THEM ALL