you will have to pull the box if you have serious clutch trouble which is what it sounds like to me. If it has a lever and cable under the box make sure it is adjusted properly, just a little free play at the cable, and there's no harm checking the pedal end that all is well up there. disconnect the cable by unscrewing the adjusting nut and make sure the cable slides freely in the outer, and grease it well.
I have a very old Ducato 10 box that must have done hundreds of thousands and the synchro cones all seem good and there was no swarf in the oil when I drained it off so I presume the synchro is not prone to wear on these boxes.
Removing this box is not complex but getting the spares it may need may not be easy, Fiat agencies are disposing of many spares prior to 2000 or so by simply dumping them in a skip.