Kubota TG1860 idler tension

[psk125]

Took the mower off the tractor last fall to mount the quick-hitch and snowblower. Noticed then that the idler pulley arm seemed really loose, so snugged it up since it wouldn't be needed for the snowblower (different belt). The instructions also called for removing the tractor's "original belt guide" and replacing it with a 12mm 1.25x30 hex bolt, which I did. Am now re-attaching the mower and am not sure where the belt guide goes - it's all dark and there are several hex bolts under there. The drawing I have is not clear and I can find no parts diagram that includes the belt guide. Does it go between the power pulley and the idler, or between the mower and the drive pulley? The snugged-up idler pulley arm also seems to put the pulley above the path of the belt so that it flies off the idler pulley less than a second after engaging the clutch. Is the idler pulley arm supposed to be loose so that the pulley hangs lower? The grass is growing faster than my progress on this mower.