It's common for the tonearm lift to begin rising and falling too quickly on old turntables. This makes cueing difficult and can damage your records if the needle hits the record at high speed. I managed to fix this problem on my Technics SL-1300 and thought I would share the process. It's similar to what's shown in this video but more complicated. I believe the Technics SL-1311, SL-1401, and SL-1411 have the same tonearm so this would work for them as well.
Most old turntables use a piston filled with high-viscosity fluid to create the lift's slow, smooth motion. Over time this fluid dries out and needs to be replaced. I read several forums where folks suggested 300,000 cst or 500,000 cst silicon differential fluid for this purpose. This is sold at hobby shops and turntable parts sites, but the cheapest I could find it was on Amazon for $9:
The greater the viscosity (cst) the slower the arm will move. I read on a forum that 500,000 cst is better for s-shaped tonearms and 300,000 is best for lighter, straight arms so I went with 500,000 cst. After finishing the repair, I think either would have been fine. 500,000 cst is very slow.
First step is to disassemble the table. Page 3 of the service manual (available at Vinyl Engine) has great instructions for this:
After opening up the table, the first step is to remove the plastic lift. The lift is spring-loaded from the bottom. Look closely at the top of the lift and you will see a black, hex-head screw (seen in the photo below). Press down on the lift to allow the screw to extrude from the plastic lift. Remove the screw and the lift will come off.
When re-assembling, this screw sets the height of the tonearm lift. It is very important that the lift not be contacting the arm when you are playing a record. Further instructions will be given about this later.
Next remove the arm assembly from the base. There are three black screws that must be removed; one of them is hidden under a plastic cap. Be careful not to damage the arm wires. You can bend the cable clamp attached to the base in order to remove the cable (and thus the entire assembly) from the turntable base. Sorry I didn't take photos of this.
Turn the arm assembly upside down. The next step is to carefully remove the anti-skate lever. The spring will remain attached to the arm, so you just need to set the lever slightly aside so you can reach the plate that's beneath it. Remove the screw and washer shown here:
Next, you must remove the two screws holding the plate that has the arm lift piston on it, seen below. Once you remove these screws, the plate should lift right out. Be careful not to damage the anti-skate spring and lever. Also make sure that you do not move the arm lift lever while this plate is removed. It needs to stay in the same position for when you reassemble.
Once the ring is off, remove the washer and spring. Then remove the brass shaft from the hole. Clean off all old damping fluid:
Once the old fluid is removed, coat the shaft with new damping fluid. Insert the shaft back into the hole and wipe off excess fluid. Make sure the piston will slide slowly back and forth in the whole.
Perform all steps in reverse to completely reassemble your table, including the cartridge. Now take another look at the tonearm lift. Remember I said the black, hex-head screw is used to set the height of the lift. You need to make sure the lift does not contact the arm while playing a record. With the power off, place a record on your table and place the stylus on the record with the cueing lever down so the stylus contacts the record. Make sure there is a tiny gap between the rubber part of the lift and the piece of plastic that connects to the tonearm and rests on the lift, as seen below.
You will now have a perfectly damped tonearm lift!