My barracuda won't keep moving and i notice there are bubbles in the return valve

its not uncommon to get some bubbles when using sectional hose as there are 12 connections that must be tight (but usually leak a bit). if you have access to a regular one piece hose, try using that to see if the problem corrects.
these machines are horrible for diaphragm problems which is why there is usually a big bin of replacements at every pool store. even though there is no tear, the rubber may have stretched or become rigid (water balance causes this)

You probably just need to redirect the returns in the pool. If they are angled right (or wrong) they will get a current moving in the pool and cause the cleaner to go to one spot and keep it in just that area of the pool.

Before you go anywhere I would check each piece of hose for leaks. If they are all OK then you need to plug off one end of the suction line and pressure it up at the other end. If the pressure drops then you have a leak in the line. I would check the fitting at the front of the pump first. Short of a cracked pipe that is where most suction leaks occur. This being a vinyl liner pool it could also be just behind the wall also.
If the hoses are Ok and it's not at the front of the pump you may want to get a leak detection service in to help find it. Good luck.

If you are seeing air bubbles in the leaf pot on the pump, you have an air leak on the suction side somewhere between the pump and the pool. Check the pump lid o-ring for any dirt, leaves, etc. Make sure the O-ring on the lid is not cracked, dry (lubrication like Aladdin's Magic Lube) or compressed or flattened. Also check your union or threaded connections to the pump suction (end) to insure they are tight and sealed. If this is an in-ground pool, and equipped with valves to control skimmers and bottom suction, close each valve separately to see if the air bubbles diminish. If the bubbles diminish when the valve is closed, then the air leak is in the closed section from that valve back to the pump. If the air leak increases, the air leak is in the still open line. Since the Kreepy crawly works on suction and increases the vacuum, the air leak will become more apparent, resulting in a loss of pump efficiency and flow, resulting in lost performance on the cleaner. If so equipped, close off the bottom drain valve and increase the suction on the vac line. I can provide further details as needed, but will need more information from you regarding actual equipment layout.

what do you hook your vacuum to in the pool? does it have suction? it may be clogged. if so you can blow it out if you have the equipment. it may be you don't have enough suction and all you need to do is adjust one of your suction side valves to fix this problem. if you don't have dedicated valves you can plug one of you other suction lines to give your vacuum more suction.

built in the black bulb pump is a non return valve.That is not working so enables the fuel to run back.They are quite easy to get from your local auto spares shop.

Check suction at cleaner. Could be broken hose, bad or dirty impeller, incorrectly set valves, dirty filter, clogged line and probably a bunch more things.

First thing to check is the removal of any winterizing plugs in the return lines. Sometimes plugs are fitted inside the lines in the pool making them not obvious. Secondly, check that any valves in return line are open. Many never lube type valve handles are oppositely positioned as compared to ball valves. If the multiport valve hasn't been tampered with, then there really is no other place to look. The flows everywhere but back to pool.