Measuring/checking belt tension on a synergy n5

[Telehandler]

Every now and again im hearing what i think is the belt slapping the inside of the boom, checked the tension which i think is correct,and i have read some articles from matt botos about tension,but what is the best way to get a correct tension? currently i can get the belt to push towards each side around 5mm between main gear and boom guides!

[debrooker]

I have about 5mm on mine and I don't get the slapping sound, sure your boom isn't bent slightly - only needs a mm ?

also worth checking if your belt is 100%, no teeth missing

[Telehandler]

Daz i have checked the boom which is 100% on a glass table and have checked the belt for damaged teeth,looks to be very minimal wear on the belt ( teeth arent as defined as a new one i have here ) so im just gonna replace belt for peace of mind!

[GIXERMAN]

Belt needs to be reasonably tight, but not over tight or you will strain on one way bearing in maingear, got too mattbotos tips on his site