That low idle "tick" is normal for that engine. No worries.
I'm not sure you're pushing the brakes down hard enough before engaging the lock. On my CK20HST, if I leave the brakes on hard, it hits the pressure relief valve and I'm not going anywhere until I release the brake. The brakes can be engaged at different pressures. Make sure you push as hard as possible on both pedals and then engage the lock lever. If this doesn't keep you from knowing it's on with movement, you may need to adjust the brakes some.
John