the IC-703 service manual (2 volumes) was available today (19. Septenber 2005)
at http://www.qsl.net/icom/manuals.html

Upon any severe failure of the radio it seems to pay off looking for cold solderings in the PA. Rolf DH1SBJ measured that with only 3 W output power, the temperature rise of the FET is rather high (over 70 degrees celsius). When the soldering of Q150 is bad then cooling does not work correctly. 

Some users say that the mike gain and the compressor shall be used only after carefully adjusting the ALC level. My suggestion is to supply the radio with 9.6V instead of 13.8V or to do the Icom PA driver update (see in this section). You will have to re-adjust the driver bias voltage (see in the IC-703 mods section).

The part list for the final stage (prices in Singapore $$, September 2005):

UPC2709(T) IC, SMD MMIC IC-703 HF LOW LEVEL AMP
IC101 MAIN
Code : (1110004080)
Model name : UPC2709T-E3
Unit Price S$3.00
Require  : 1pc to repair the main unit on IC-1

MA77 DIODE, SMD RF SW IC-703 RX/TX DRIVE SW D101 MAIN 
Code : (1790000620)
Model name : MA77 (TX)
Unit Price S$0.50
Require  : 1pc to repair the main unit on D101.
This spares require a minimum quantity order of 10pcs.
 
2SK3074 TRANSISTOR, SMD FET IC-703 PREDRIVER Q101 PA
Code : (1560001100)
Model name : 2SK3074 (TE12L)
Unit Price S$3.00
Require    : 1pc to repair PA Unit on Q101

RD01MUS1 TRANSISTOR, SMD FET IC-703 DRIVER Q150 PA
Code : (1560001240)
Model name : RD01MUS1
Unit Price S$3.00
Require    : 1pc to repair PA Unit on Q150

For soldering & desoldering: 
- Chipquick 
- a temperature regulated soldering iron 
- binocular glasses.

You may find more information on that if you do a keyword search in the forum.