E280 is only getting one front gear and reverse what has happened

Front wheel drive vehicles have what are called transaxles. They have bearings in them that are bad which is the clicking noises you are hearing. Need to get it to someone who is automobile savy. And has done them before .They can be difficult . But they will eventually leave you stranded on the road side if you don't have them fixed.

bad bearing or axle shaft possible

On some European cars there is just one shaft from the gear shift leaver that operates the transmission. First make sure all the bushings are good unlike American cars European cars are not forgiving for loose or worn bushings. On the cars with cables there are two cables on for going forward and backward one for going side to side; not the gear position how they move the Mechanisms Make sure the bushings are not loose or worn and check cables for breakage. Make sure to check under the rubber boot usually by removing the center cover between the two seats if the cable or mechanism has broken it usually near the shift inside the car. Usually the pressure for going side to side is equivalent for going back to back there should also be a click feeling as you move the rods in the transmission by moving the stick both sideways and front to back. If it is not the cables or the outside mechanisms it usually is one of keys usually a screw in the detent mechanism in the transmission which means the transmission has to come out. Unfortunately they stopped making that serviceable in the 1970's. A 1950's Chevy for example has that mechanism on the side of the transmission instead of on top.

On your type of transmission the top where the gear shifter sit at is where the solution is at.you will have to pull the rug back take out the gear selector housing once its out, the reverse relector is held by a 3/4 to 11/16 reverse nut it came loose, that relator has interfered with the gears when this happens it basically just goes in reverse

seems like faulty transmission, the reason is when you drive the car gears are up shift form 1 to 2 , 2 to 3, 3 to 4, 4 to 5, like that it should be 7 speed auto trans mission in your car, if you mention when which gear up shift the problem occurred I can give more information about what's the fault in transmission, so according to your details it's like two gears are engage together, when two gears are engage same time the transmission control unit understand it's something getting wrong in the transmission according to actual value of gear ratio, then trans mission change the gear to neutral for a second and after that it give the one lower gear than the gear which was stuck and drive fine, this thing might not happen all the time but is the problem verse it can happen all the time, the solution is you must get your car to the Mercedes dealer workshop then they can find what's the wrong inside the transmission before remove it, they have advance diagnose tool for it, then they will repair your transmission, this is the cheapest way, if some one repair your transmission without right understanding regarding what's the exactly fault you will be stuck, may have to be remove again and again,

lincage rod inside the gear box will have bent it happens when to much preasure is applied commen for jamming up thow.

I had this problem or at least a similar symptom. Check the wiring harness located behind left front tire for wear or brakes. I had a broken wire from the tire rubbing this harhess of wires. when I repaired it, I had all forward gears and reverse. To find the spot, Just look for a spot that the front outer edge of the tire could hit. Hope this helps.

does it happen turning both directions? AND...does it happen turned the same angle in forward gears? Can you feel it in the pedals, floor, your seat or through the shifter? You may want to grab a helper and take them to a business/industrial area that has an empty parking lot and have them stand out side the vehilcle while duplicating the symptom. See if you can roughly locate where the sound is coming from. e.g. right front, left front. under center of vehicle. Your helper may need to walk or run near the vehicle while backing to be closer to the noise while it occurs.

youre on your way to the tranny going out on the car

Regarding the reverse problem. If it's not going into reverse at all and the shifter seems to come up against a dead stop then it's probably the 5th gear synchro. I've recently had the same problem with my 99 prelude. The first time it happened I changed the reverse shift fork because the mechanism was worn. This worked for a while, however, the same thing happend a short while ago. I took my gearbox apart and a friend pointed out that there were some score marks on the synchro. I changed the 5th gear synchro, which is on the same selector rod as reverse gear. This has cured the problem. The synchro cost me £140 from Honda. Hope this is of some help to you.