Hi. I am writing to ask for some help with a vehicle I have recently bought. It is a manual 2017 Mazda 3 diesel with 35,000 miles on it and I have noticed that the gear change doesn’t feel right. I have observed the following behaviour:

1. The gear stick is stiff to change between gears and feels like it is catching or dragging as it changes between gears. It can be very noticeable when selecting 1st, reverse or changing to second and 6th but occurs on all gear changes. It feels notchy and inches several clicks before engaging the gear rather than one smooth action.
2. It can be difficult to engage 1st/reverse gear from standstill with the clutch on the floor or to change to 2nd gear. It feels like the gear stick is blocked from selecting the gear even though it is in the right rev range.
3. The biting point seems to vary from being low to being at the end of the clutch pedal travel. The clutch pedal can feel easy to press or very heavy to press and can suddenly bite much harder even after the biting point has engaged. It is very difficult to have a smooth gear change.
4. When manoeuvring in reverse where the clutch is up it doesn’t feel like it is biting very much and it is hard to move the vehicle. Lifting the pedal more doesn’t seem to make it bite more.
5. There has been some vibration experienced through the clutch pedal even when depressed.
6. The car jerks when lifting off the accelerator even at the slightest movement of the pedal in higher gears. Further it feels like there is some jerking in the transmission when accelerating or cruising.

This behaviour is unlike any I have experienced on other vehicles I have driven. When this isn’t happening, the gears can be really slick and smooth and easy change with no resistance and it is easy find the biting point.

What could the issue be caused by and are there any easy diagnostic tests that can be run to identify the possible issue? Is this something that should be diagnosed by a mechanic or would I need to see a specialist?