The receive on this radio can be described as constrained to say the least. There are loads of mods listed on the web to increase receive gain and make the radio less constricted, some good, some bad and some indifferent. The few mods that I will list here have been done to my own radio and have definately improved things.
Swap Q101 - 2SC1674 for 2SC2999: Improved signal to noise ratio, weak stations that were in the noise can now be heard. Signal meter used to sit at 5 on an empty channel but now is at 0. Also squelch used to "chatter" at the point of cutoff, but now works fine. The only downside to this mod that I have noticed is that the signal meter becomes less accurate.
UPDATE: I got annoyed with the signal meter not reading right and readable signals not getting through the squelch, so decided to put the transistor back to the original 2SC1674.
With a new 2SC1674 I got all the benefits and nearly as good S/N ratio as with the 2SC2999 (obviously the original 2SC1674 was worn out), the signal meter came back right and the squelch let the weaker readable signals through. I have since found out (thanks to James) that there are a load of fake 2SC2999's on the market. So, Before modding your radio I suggest you try fitting a new 1674 first, as this has given me good results and you may not need or want to modify your radio.
Alternative for 2SC2999: As there are a lot of fake 2SC2999 transistors on the market and it is not easy to tell a fake transistor unless you got a load of hi-tech kit, I wanted to find a suitable replacement which would work well in this situation. On one of the forums I use, it was suggested to use an (NEC) 2SC3356 in the place of Q101 (2SC1674). The 3356 transistor is a tiny surface mount device but it can be fitted to the solder side of the Lincoln board as per pic on the right. The blue line being a link wire.
I have fitted one of these to my Lincoln and it seems to work ok. Try to get a 2SC3356 with the suffix R25/S (the transistor is marked R25) instead of R23 or R24 as the R25 has higher gain.
UPDATE: After using the radio for a while with the 2SC3356, I will be replacing the 2SC1674 (standard transistor). The 2SC3356 works ok and certainly better than the 2SC2999, but readable signals aren't breaking the squelch and thats a pain. The 2SC3356 may well have better specs over the 2SC1674 on paper, and maybe it shows higher gain when tested, But in real world tests with the transistor in the radio I have to say that the original 2SC1674 is the best. Before modding try fitting a new 1674 first, you may be surprised!
Swap C412 (on FM board) 47n for 10n: opens FM de-emphasis bandwidth giving a much cleaner and brighter tone to all FM signals, making weaker stations easier to hear. This is 100% recommended, a must if you use FM a lot.
Swap C35 0.039 for 0.022uf: For more treble on recieve audio. Makes radio sound less constricted.
Swap C36 0.0068 for 0.1uf: For more bass on recieve audio. Makes radio sound less constricted.
There are many more recieve mods on the web. These mods will make your radio sound a heck of a lot better and you may not need or want to do any other mods after these.