An unexpected loss of contact with SOHO occurred on 25 June 1998. The mission
   was recovered and normal operations resumed in mid-November 1998. Despite
   subsequent failures of all three gyroscopes (the last in December 1998),
   new gyro-less control software installed by February 1999, allowing SOHO to
   resume normal operations (and making SOHO the first 3-axis-stabilised
   spacecraft to operate without a gyroscope).
[...]

SPACECRAFT TRAJECTORY (concatenated trajectories from GSFC FDF):

  For the time-span 1998-Aug-19 to 1998-Sep-25, there is no official
  trajectory information due to the recovery effort. Therefore, the initial
  state at resumption of operations 1998-Sep-25 was integrated back to
  August 19 assuming a purely ballistic trajectory. Trajectory errors
  during this interval may be significant due to unmodelled dynamics.

  Trajectory name             Start        Stop
  --------------------------  -----------  -----------
  soho_1995                   1995-Dec-02  1996-Jan-01
  soho_1996                   1996-Jan-01  1997-Jan-01
  soho_1997                   1997-Jan-01  1998-Jan-01
  soho_1998a                  1998-Jan-01  1998-Aug-19
  soho_1998a-b_gap            1998-Aug-19  1998-Sep-25 (ballistic filler)
  soho_1998b                  1998-Sep-25  1999-Jan-01 (recovery of contact)
  soho_1999                   1999-Jan-01  2000-Jan-01
  soho_2000                   2000-Jan-01  2001-Jan-01
  soho_2001                   2001-Jan-01  2002-Jan-01
  soho_2002                   2002-Jan-01  2003-Jan-01
  soho_2003                   2003-Jan-01  2004-Jan-01
  soho_2004                   2004-Jan-01  2005-Jan-01
  soho_2005                   2005-Jan-01  2006-Jan-01
  soho_2006                   2006-Jan-01  2007-Jan-01
  soho_2007                   2007-Jan-01  2008-Jan-01
  soho_2008                   2008-Jan-01  2009-Jan-01
  soho_2009                   2009-Jan-01  2010-Jan-01
  soho_2010                   2010-Jan-01  2011-Jan-01
  soho_2011                   2011-Jan-01  2012-Jan-01
  soho_2012                   2012-Jan-01  2013-Jan-01
  soho_2013                   2013-Jan-01  2014-Jan-01
  soho_2014                   2014-Jan-01  2015-Jan-01
  soho_2015                   2015-Jan-01  2016-Jan-01
  soho_2016                   2016-Jan-01  2017-Jan-01
  soho_2017                   2017-Jan-01  2018-Jan-01 (prediction Dec20-Jan01)
  soho_2018                   2018-Jan-01  2018-Dec-03 (prediction after Sep 9)